^ • • + * ,,r- • A+ .FR0108547 Commissariat a I Energie Atomique Direction des Sciences de la Matiere Departement de Recherche sur I'Etat Condense, les Atomes et les Molecules CEA-DREC AM-SPAM-RA-1998-2000
Service des Photons, Atomes et Molecules
Activity report 1998-2000 33/04 COMIVIISSARIAT A L'ENERGIE ATOMIQUE Direction des Sciences de la Matiere Departement de Recherche sur l'Etat Condense, les Atomes et les Molecules Service des Photons, Atomes et Molecules
SPAM
ACTIVITY REPORT 1998 - 2000
Centre d'Etudes Nucleaires de Saclay 91191 Gif Sur Yvette Cedex France GS3 VWX«>S«^ SACLAY Direction des Sciences de la Matiere Service des Photons Departement de Recherche sur 1'Etat Condense, Atomaset Molecules les Atornes et les Molecules Service des Photons, Atomes et Molecules
Head of the Laboratory
Tel: (33) 1.69.08.24.73 Didier NORMAND Fax : (33) 1.69.08.87.07 Email : [email protected]
Head Assistant of the Laboratory
T61: (33) 1.69.08.68.43 Jean-Paul VISTICOT Fax : (33) 1.69.08.84.46 Email : [email protected]
Secretaries
T61: (33) 1.69.08.74.09 Jacqueline BANDURA Fax: (33) 1.69.08.87.07 Email : [email protected]
Tel: (33) 1.69,08.93.91 Sandrine JACQUART Fax: (33) 1.69.08.87.07 Email : [email protected]
Safety Engineer
Tel: (33) 1.69.08.82.60 Pascal d'OLIVEIRA Fax : (33) 1.69.08.87.07 Email : [email protected]
Service des Photons, Atomes et Molecules http://www-drecain.cea.fr/spam HEADS OF GROUPS FEMTOSECOND LASER FACILITIES Pascal d'OLIVEIRA
Pascal d'OLIVEIRA T61: (33) 1.69.08.82.60 Fax : (33) 1.69.08.87.07 [email protected]
MATTER UNDER EXTREME CONDITIONS Bertrand CARRE
Laser matter interaction in strong fields Bertrand CARRE T61: (33) 1.69.08.58.40 Fax : (33) 1.69.08.87.07 [email protected]
High energy density matter and atomic physics Thomas BLENSKI T61: (33) 1.69.08.96.64 Fax : (33) 1.69.08.87.07 blenski @drecam.cea.fr Applications of plasmas Martin SCHMIDT Tel: (33) 1.69.08.26.57 Fax: (33) 1.69.08.87.07 [email protected]
PHYSICAL CHEMISTRY OF MOLECULAR SYSTEMS FRANCIS PERRIN LABORATORY Jean-Paul VISTICOT Dimitra MARKOVITSI
Photophysics and photochemistry in the gaseous phase Jean Paul VISTICOT (33). 1.69.08.68.43 (33)1.69.08.84.46 [email protected]
Nanometric covalent systems Cecile REYNAUD (33)1.69.08.69.16 (33)1.69.08.87.07 revnaud@ SDam.saclav.cea.fr
Theoretical chemistry Jean-Pierre DOGNON (33)1.69.08.37.14 (33) 1.69.08.87.07 [email protected]
Synchrotron radiation Paul MORIN (33) 1.64.46.81.24 (33) 1.64.46.81.24 [email protected]
Photo-physical chemistry in the condensed phase Dimitra MARKOVITSI (33)1.69.08.46.44 (33)1.69.08.87.07 [email protected]
Service des Photons, Atomes et Molecules http://www-drecam.cea.fr/spam PLEASE BE AWARE THAT ALL OF THE MISSING PAGES IN THIS DOCUMENT WERE ORIGINALLY BLANK TABLE OF CONTENTS
General informations 3 Introduction 7
I HIGH INTENSITY AND HIGH FLUX PHOTON SOURCES 15
1-1 General presentation 17 1-2 Femtosecond Laser Facilities and laser driven VUV-XUV 18 sources 1-3 Synchrotron sources and Free Electron Lasers 24
II MATTER UNDER EXTREME CONDITIONS 31
II-l General presentation 33 II-2 Production of coherent XUV light by harmonics generation 34 H-3 Molecules and clusters in strong fields 42 II-4 Ultra-short non LTE plasmas produced by Optical Field 50 Ionization II-5 High energy density matter and atomic physics 55
III PHYSICAL CHEMISTRY OF MOLECULAR SYSTEMS 61
HI-1 General presentation 63 in-2 Photophysics and Photochemistry in the Gaseous Phase. 64 ni-3 Photo-physical chemistry in the condensed phase 71 IH-4 Nanometric Covalent Systems 75 m-5 Physical Chemistry with Synchrotron Radiation 82 HI-6 Theoretical chemistry 88
Service des Photons, Atomes et Molecules http://www-drecam.cea.fr/spain IV SCIENTIFIC COMMUNICATION 93 (January 1998 - June 2000)
Articles in refereed journals 95 Articles in proceedings 109 Book chapters 113 Invited conferences 115 Invited seminars 121 Oral communications 127 PhD Theses 135 Popularization articles 137 Patent 138
V SPAM WITHIN THE SCIENTIFIC COMMUNITY 139
Scientific awards 141 Networks and contracts 143 Relations with Universities 147 • Corresponding Research Laboratories 147 • Teaching 149 • Reception of University students and other scholars 151 Collaborations with other laboratories 153 Post-docs 155 Foreign visitors 156 Organisation of conferences and workshops 157 Evaluation of research 159 • Evaluation of laboratories, program committees and evaluation 159 committees • Thesis committees 161 • Young scientist seminars 165
List of the laboratory staff 169
Service des Photons, Atomes et Molecules http://www-drecam.cea.fr/spam SPAM Activity Report 1998-2000 Introduction
The aim of this introduction is to outline the main developments of the 'Service des Photons, Atomes et Molecules', (SPAM) during the 1998-2000 period: developments in terms of structure, staff, science, collaborations and contracts. SPAM is one of the laboratories in the De"partement de Recherche sur l'Etat Condense", les Atomes et les Molecules (DRECAM), itself depending on the Direction des Sci- ences de la Matiere (DSM) of the CEA Institution.
1. Structure SPAM structure has been extensively modified during the period of reference. SPAM was previously divided into six scientific groups plus the Department laser facility LUCA (Laser Ultra Court Accord- able) and the tool shops. It is now organized in three large groups, that is two research groups interact- ing with one technical group, as shown in the diagram below. This reorganization meets the spirit of the last Scientific Council recommendations.
SPAM D. Normand | ..J,. . _ J , >second Laser Facilities Matter under Extreme Physical Chemistry of Conditions Molecular Systems P. d"Oliveira B.Csrri J.-P. Visticol | I . . . . 1 . . .. 1. . Saclay Laser-matter Laboratoire Interaction Center Francis Perrin
(SLIO D. Markovitsi
The "Femtosecond Laser Facilities" technical group (Gl) is headed by Pascal d'Oliveira. It is composed of LUCA, which is a versatile multi-beams tunable laser facility, UHI10, which is a 10TW laser facility, and the technical support. The "Matter under Extreme Conditions" group (G2), headed by Bertrand Carre", studies physical problems relevant to laser-matter interaction under strong field and plasma physics; topics of inter- est include High order Harmonic Generation (HHG) and applications, Coulomb explosion of mole- cules and clusters, laser-produced plasmas at ultra-high intensity and high-energy plasmas. The "Physical Chemistry of Molecular Systems" group (G3) is headed by Jean-Paul Visticot. It groups together the physical-chemists of SPAM. The topics studied deal with photophysics and photochemistry, nanometric covalent systems, theoretical chemistry, interaction of matter with syn- chrotron radiation, Fret; Electron Laser (FEL) development and applications.
This report is divided in five chapters. Chapter I gathers all the work performed on the light sources, that is to say the evolutions of the femtosecond laser facilities (Gl group) and the achievements on the new SU5 synchrotron line and on the Free Electron Laser (part of G3 group). Chapters II and HI fo- cus on the scientific results obtained by the G2 and G3 groups respectively. Chapter IV gathers all information on SPAM scientific communication while Chapter V lists SPAM interactions with the sci- entific community.
In addition to enhancing collaborations within the groups, the three-group structure was introduced to support SPAM's new organization policy. Gathering all SPAM activities in Physical Chemistry in the G3 group has been very useful for including it into a Mixed Research Unit (French UMR) with CNRS and Paris XI University. This unit called the "Laboratoire Francis Perrin" has been accepted by CNRS and will be officially formed by the end of 2000. Another important aim was to obtain the status of Large European Infrastructure for an ensemble of four laser facilities (including LUC A and UHI10) grouped inside a common organization named 'Saclay Laser matter Interaction Center, (SLIC)'. This attempt followed a recommendation of our last Scientific Council "to coordinate future efforts in laser development and applications with other in- stitutions". A proposal was submitted by SPAM to the European Union in May 1999. It was supported by 70 letters from international scientists who declared their intention to perform experiments at SLIC. Although rejected by the EU in 1999, the SLIC project continues to be viable and will be resubmitted (cf website http://www-drecam.cea.fr/spam/aspam5.htm). A first step was made in 2000 when SLIC was accepted as part of a large cluster including all the European laser infrastructures.
In spite of the three-group structure, scientific and technical collaborations between the groups are very active. Collaboration is very tight on molecule and cluster science for which researchers of G2 and G3 groups share two "Laboratoires de Recherche Correspondants" (LRC) contracts with Paris VI and Lyon I Universities. The applications of high order harmonics take full advantage of the complementary cultures of Physicists and Physical Chemists. From the technical point of view, the groups share the laser facilities of Gl, the Super ACO synchrotron source, vacuum and supersonic jet technologies. The search for ultra high-quality mirrors interests the Free Electron Laser as well as the HHG communities.
2. Staff The chart in Figure 2 gives the comparison of the SPAM staff between June 98 and December 2000. The number of CEA researchers/engineers has increased from 37 to 43, that is a net gain of 6 units; the number of technicians/administrators has decreased from 13 to 12; the number of CNRS researchers has increased from 2 to 6. In all, the number of permanent fellows has increased from 52 to 61 between June 1998 and December 2000, which restores the population that SPAM had in 1995. The numbers of PhD students and post-docs are slightly reduced but remain satisfactory.
CEA CEA CNRS PhD Students Postdocs Researchers- Technicians- Researchers Engineers Administratives
Figure 2: Evolution of the SPAM staff between June 1998 and December 2000
The detailed analysis is the following - Five researchers have retired and five young researchers have been hired. Two of them are involved in SPAM efforts to intensify its research in high-energy laser physics. Plans are for these col- leagues to join the group that DSM intends to create at Bordeaux to support civilian research on the "Ligne d'Inte"gration Laser" (LfL) and the Laser M6gaJoule (LMJ). - Three CEA researchers have joined SPAM. - Three SPAM technicians have been promoted to engineer positions. - Although one technician and one secretary have been hired during the period of reference, the num- ber of technical staff has slightly decreased due to the promotion of three technicians. - As a result of the creation of the Francis Perrin Laboratory, four CNRS researchers joined SPAM by July 1999. Other researchers are expected to join when LFP is officially formed. DCNRS Researchers • CEA Technicians-Administratives DCEA Researchers-Engineers
< 30 30-34 35-39 40-44 45-49 50-54 55-59 > 60 Figure 3: Age pyramid of SPAM permanent staff (December 2000)
The age pyramid (Figure 3) shows that 87% of the permanent staff is below 50 years old, with an av- erage age of 42 years at the end of 2000. Very few retirements are expected in the next few years. Al- though the researchers/engineers staff peaks at 45-49 years, more than 40% of this category is below 40. The technical staff is very well balanced between the different age groups.
3. Science and Technology The evolution of science and technology at SPAM is described in detail in the first three chapters of this report. Without giving an exhaustive list here, it is nonetheless possible to emphasize some major achievements obtained during the 1998-2000 period: The LUCA facility has been notably upgraded. Its pulse duration has been reduced to 60 fs, its peak power increased to 2 TW, and it can now accommodate 5 experiments simultaneously. The UHI10 facility has come into full operation, many diagnostics have been implemented and a probe laser line has been constructed. The FEL has successfully operated at 300 nm. Finally, SPAM has participated in trie construction and characterization of a new synchrotron line (SU5) that features very high resolution and adjustable polarization. The G2 group has developed two new applications in surface physics and in laser-plasma physics that take full advantage of the high-order harmonics properties. It has made important progress in the search for a new X-ray laser scheme using optical field ionization. It has strongly intensified its efforts in laser-plasma interaction studies by conducting experiments at Ph6bus and at LULI (Laboratoire pour l'Utilisation des Lasers Intenses), by performing dense-plasma absorption calculations and by developing applications for nanolithography. The G3 group has observed the solvation dynamics of inorganic salts and the pre-reactive behav- ior of photoexcited alkene molecules at the femtosecond scale. The energy transport in organized molecular systems has been characterized; this work will be now oriented towards biomimetic systems. Evidence for the existence in cosmic dust of nanocrystallites (diamond and silicon) has been found. Finally, calculations of charge transfer in ion-molecule systems have emphasized the importance of this term in the modeling of metal cations solvation.
4. Collaborations and Contracts The diagram in Figure 4 shows the main collaborations and contracts of SPAM both on basic research and on more explicitly applied research, although this partition may be somewhat arbitrary, National and International Laboratories CNRS. Paris VI. Pans XI, Bordeaux, Lyon I. Orleans, Caen Universilies Most countries of (he European Union. 1:SA. Japan. Russia
High Harmonics X Laser Opjcilie*;
Sopra Stso \ InJust Rtosc Thomson
Figure 4: Collaborations of SPAM in basic and applied research
Basic research. On the one hand, SPAM has strongly increased its collaboration with academic laboratories, the main achievement being the creation of the F. Perrin Laboratory with the CNRS and the Paris-Sud Univer- sity. In addition, our four previous 'Laboratoires de Recherche Correspondants' (LRC) contracts with Bordeaux, Orl6ans and Paris VI Universities have been renewed for two more years; two new LRC contracts have been signed with Lyon I and Paris VI Universities. A Research-Teaching convention has been signed between CEA/DRECAM and the Molecular Physical Chemistry program of the Paris-Sud University. As a result of this convention, SPAM developed a complete experimental set-up including laser vaporization and spectroscopic detection. This set-up devoted to student formation was released to the University in September 1999. In addition, SPAM is involved in a National Program between CEA, CNRS and CNES on the Physical Chemistry of the Interstellar Medium (PCMI).
On the other hand, SPAM has obtained several contracts from the European Union. It is involved in five TMR (Training and Mobility of Researchers) networks (Generation and Applications of Ultra- Short X-ray pulses, SRFEL source at 200 nm, ATTO, an X-Ray Laser Network), one NANOMAT thematic network and one Access to Research Infrastructure network (combined SR and VUV FEL Facility).
Different collaborations also exist between SPAM and several laboratories of the Military Application Division (DAM), formalized through the co-funding of PhD thesis works. They range from the devel- opment of coherent extreme UV sources and characterization of optics to the studies of opacities in dense plasmas. Finally, the "Groupe dTnvestigation des Applications Scientifiques des grands lasers" (GIAS), in charge of promoting the civilian research on the LIL and LMJ facilities, includes contribu- tion of SPAM to, for instance, astrophysics, nuclear physics and plasma physics programs.
More applied research SPAM has made many efforts to find new contracts on more applied research in order to open its ac- tivity to its scientific and technological environment. These research lines are indicated by black arrows in Figure 4. SPAM honors its affiliation to the CEA by interacting with several other CEA Divisions. In 2000, SPAM signed three contracts with the DCC (Fuel Cycle Division) for consulting expertise in the Laser Isotope Separation (SILVA) program. These contracts concern some specific aspects of the laser
10 propagation in dense media, of ion collisions in the separation process and the search for new dye mole- cules dissolvable in water rather than in methanol.
In the context of the CEA efforts on nuclear waste disposal, SPAM has also begun a three-year re- search program on "extracting molecules" that deals with the modeling of metal ion-molecule interac- tion. The ultimate goal is to define new molecules for extracting heavy metal ions among other constitu- ents in order to facilitate their storage. This program started in 1999 and involves other CEA laborato- ries in the DSM, DCC and DSV (Life Science) Divisions.
Since November 1999, SPAM has been part of a national R&D project called PREUVE that aims at developing the future technology for nanolithography processing. PREUVE is a two-year pre-industrial program that involves three CEA laboratories, one CNRS laboratory, Marseille University and three industrial companies. SPAM efforts concentrate on developing an intense Extreme UV light source at 13nm based on laser-clusters interaction. At the first stage, the source will operate at low repetition rate (<100Hz). It will be inserted in the French EUV lithography test bench that is being developed in par- allel by other PREUVE partners. This bench will allow for experimental studies on EUV lithography and photo-resist processes.
: II subvention (MF) • contracts (MF) Figure 5: Evolution of the SPAM subven- tion and contract funding over the 1998- 2000 period, excluding salaries of the per- manent staff
1998 1999 2000 Figure 5 displays the SPAM subvention including all budget lines such as investment, running costs, travel costs and salaries of non-permanent staff. The permanent staff salaries amount to about 22 Mil- lions Francs (MF) per year, which represent 80% of the total subvention. The diagram also shows the internal resources of SPAM from contract funding over the same period. The part of the subvention considered in Figure 5 has decreased by 16% between 1998 and 2000. Furthermore, the fraction corre- sponding solely to the investment and running costs has decreased by 25%. In 2000, it amounts to about 3 MF, which is less than 50kF for each permanent fellow. A very substantial increase of our in- ternal resources - by a factor of 5 - and a drastic reduction of our investments have made it possible to maintain the level of most research activities in 2000. Yet SPAM budget situation remains hazardous because it relies on a few big contracts and because contract funding is by definition targeted on spe- cific goals and cannot be used to support all laboratory's activities
5. Future Many large projects must be undertaken in the years to come. The PREUVE project will end in No- vember 2001. In order to meet the requirements for future industrial stepper machines, it is necessary to prepare the next stage that requires developing a high repetition rate (>lkHz) extreme UV laser plasma source. SPAM, CEA/DCC and the CEA/DTA are already negotiating with several partners from Germany and the Netherlands to submit a common project to the European Community as part of the MEDEA+ program. The intention announced by Thompson TCL of manufacturing such an extreme UV source at high repetition rate is a highly valuable asset for the future of this research.
SPAM must re-apply to the EU for the status of large infrastructure for its laser facilities (SLIC proj- ect). For this purpose, it will be essential to emphasize the complementary characteristics of the three French laser centers in the Ile-de-France region: SLIC offers unique possibilities of combining several laser lines widely tunable from XUV to infrared, trie Laboratoire d'Optique Appliquee (LOA) features
11 the shortest pulse duration and highest peak power, and the LULI is specialized in high energy lasers at low repetition rates.
SPAM is heading a project entitled "Plate-forme Laser Femtoseconde Accordable" (PLFA) which aims at increasing the tunability of its laser facilities. Two new laser systems will be added to the LUCA fa- cility. The first laser will be a tunable source based on Ti:Sapphire kHz amplifier delivering 0.3 TW ultra-short pulses. This system is more specifically designed for two-color (IR/VUV-XUV) pump-probe experiments. The second system will give access to the mid-infrared spectral range by means of fre- quency difference between two parametric amplifiers. The PLFA project has been presented to the Ile- de-France region in January 2000; the demand for funding will be submitted at the end of the year.
It is necessary to find new directions of research. SPAM is contributing with several European partners to a theoretical chemistry project to develop accurate quantum chemical methods relevant to large mo- lecular systems containing actinides or lanthanides. Model potentials for molecular dynamics simula- tions should be developed, not only for nuclear waste management (a collaboration with the Fuel Cycle Division is in project for 2001) but also for further work in environmental or life sciences. The recent arrival of chemists specializing in the liquid phase should also make it possible to develop new topics at the interface of physics and biology. Other possible tracks concern the applications of laser-produced plasmas (EUV light and energetic charged particles sources - see Sections II-3 and II-4) and the new source of size-selected nanoclusters (see SONATE experiment in Section III-4), which is developed to study size-effects on the structural and optical properties of covalent clusters.
Finally, science at SPAM is linked to big and exciting projects like SOLEIL, the LIL and LMJ lasers. France's recent decision to build SOLEIL on the Saclay plateau will give SPAM the opportunity to pursue its researches using third generation synchrotron sources in the best conditions. The challenge is to continue experiments in LURE and in other European synchrotrons and to optimize the equipments to be transferred to SOLEIL around 2005. As far as science with big lasers is concerned, SPAM hopes primarily to put its expertise in laser-matter interaction in strong laser field to work in the physics of matter with high energy density, either for the study of plasma diagnostics or for the physics of fast ignition.
As shown in this introduction, SPAM and science at SPAM have developed appreciably during the last two years. SPAM hopes to remain a laboratory of basic research with well-targeted expertise in physics and physical chemistry of light-matter interaction. The dynamism and the multiple expertise of its re- searchers, an effective technical support, and cutting-edge equipment have allowed SPAM to contribute substantially to several major projects of the CEA, as for example the electronics of the future, large lasers and their applications, enrichment processes and treatment of waste products. Serving the CEA large objectives will remain a priority for SPAM.
Acknowledgements On behalf of all SPAM researchers, I wish to thank our technical staff that provides a constant sup- port to our activity. Its expertise in design and mechanics, laser and optics, computer systems, elec- tronics and electro-mechanics, as well as its skill and efficiency are at the bases of our research. I am very thankful to the reading committee, and especially to B. Carre, I. Dimicoli, Ph. Millie, P. d'Oliveira and J.-P. Visticot who brought a sustained critical and constructive care to improving this presentation. Finally, J. Bandura, S. Jacquart and P. Meynadier, who have prepared the final form of the report, are especially and warmly acknowledged
D. Normand
12 SCIENTIFIC RESULTS
13 HIGH INTENSITY AND HIGH FLUX PHOTON SOURCES
I-l GENERAL PRESENTATION 17
1-2 Femtosecond Laser Facilities and laser driven VUV-XUV sources 18
I-2-a Introduction 18 I-2-b The LUC A Facility 18 I-2-c The UHI10 Laser Facility 20 I-2-d Production of coherent XUV by high order harmonics generation 22 I-2-e Selected references 23
1-3 Synchrotron sources and Frtse Electron Lasers. 24
I-3-a Introduction 24 I-3-b SU5: a VUV high resolution beamline with variable polarization 24 I-3-c The UV Free Electron Lasers and their applications 26 I-3-d Selected references 29
15 HIGH INTENSITY AND HIGH FLUX PHOTON SOURCES
1-1 GENERAL PRESENTATION
Most of the programs carried out at SPAM involve radiation-matter interaction and consequently, rely on photon sources. Beside commercial laser systems, four main categories of photon sources have been studied, designed, developed or upgraded by SPAM teams from 1998 to 2000. These four types of sources are Synchrotron radiation sources (SR), Free Electron Lasers (FEL), Compact VUV or XUV laser-driven sources and Intense femtosecond laser facilities.
The SPAM interest for these four categories of sources results from their complementarity. The synchrotron beamlines and the Free Electron Lasers deliver high photon flux at MHz repetition rate together with very high shot-to-shot energy stability. These two sources have the additional advantage of being naturally synchronized. Synchrotron beamlines are also the most widely tunable VUV or XUV sources and they offer the possibility of controlling the polarization of the beam, as it has been demonstrated in the VUV with the Super-ACO SU5 beam line.
Compared with the synchrotron beam lines, Storage Ring Free Electron Lasers are fully coherent sources which deliver higher brilliance beams in the UV. Their reliability as a source for users in combination with synchrotron radiation has been proven on the Super-ACO FEL. Included in high brilliance synchrotron facilities (so-called "3rd generation sources"), Storage Ring FELs should offer outstanding performances, especially in terms of average power (several watts) and brilliance in the UV and VUV range.
On the other hand, compact VUV and XUV laser driven sources require smaller installations. Generally, then- average photon flux is lower (due to their repetition rate typically less than 1kHz) but their peak power and their intensity can be much higher. For instance, with high order harmonics pulses, intensities in the 1010- 1012 W/cm2 range have been obtained at 20 nm. The high order harmonics pulses are also highly coherent and ultrashort: pulses duration of a few teas of femtosecond are now typical.
Besides the above-mentioned sources, the femtosecond laser facilities have dual interest. They generate ultrashort intense pulses for the study of subpicosecond kinematics or to investigate phenomena induced by ultra-high intensity optical fields. These intense lasers facilities are also the necessary drivers for the VUV and XUV laser-driven sources.
This chapter presents the "source" activities carried out at SPAM from 1998 to 2000. It is divided in two parts. The first part is dedicated to the femtosecond laser facilities LUCA and UHI10; it also presents briefly the performances of the XUV high-order harmonics source studied and operated at SPAM. The second part concerns high performance synchrotron radiation beamlines and Ultraviolet Free Electron Lasers. They involve mainly the SU5 synchrotron beam-line and the Super-ACO Free Electron Laser (FEL). Some of the experiments performed with the Super- ACO FEL are also reported.
17 1-2 Femtosecond Laser Facilities and laser driven VUV-XUV sources Permanent research and technical staff: P. Agostini, T. Auguste, M. Bougeard, P. Breger, E. Caprin, B. Carre, M. Ch6ret, P. D'Oliveira, S. Dobosz, A. Fillon, O. Gobert, D. Guyader, P, Meynadier, P. Monot, M. Perdrix, P. Salieres. PhD Students: L. Le DeYoff, J.-F. Hergott, S. Hulin, P.-M. Paul. Post-doctoral position: H. Merdji. Collaborations: D. Joyeux, D. Phalippou (Institut d'Optique Th6orique et Appliqufe, Orsay), Ph. Zeitoun (Laboratoire de Spectroscopie Atomique et Ionique, University Paris XI, Orsay), E. Constant, J.P. Chambaret, (Laboratoire d'Optique Appliqu6e, ENSTA, Palaiseau), E. M6vel (Centre d'Etudes des Lasers Intenses et Applications, University de Bordeaux), A. L'Huillier, C.-G. Wahlstrom (Lund Institute of Technology, Lund, Sweden),
I-2-a Introduction
The LUC A and UHI10 femtosecond laser facilities have been operated by the SPAM technical group since 1993 and 1997 respectively. UHI10 delivers ultra-intense (10 TW) pulses for the study of laser matter interactions at ultra high intensity. LUCA is a more polyvalent facility delivering ultrashort pulses in the visible, ultraviolet and XUV spectral ranges, with powers up to 2 TW (at 800 nm). The main characteristics of its XUV line, based on High order Harmonics Generation, are given in Section I-2-c (see also Section II-2 for more information on high order harmonics).
Two other kinds of laser-driven VUV or XUV sources are studied at SPAM, though not presented in this chapter. The UHI team (T. Auguste and col.) investigates a new scheme of X-ray laser. The proposed lasing medium is a plasma generated by Optical Field Ionization (OFI) of gaseous nitrogen. Preliminary studies have demonstrated that this plasma exhibited the required characteristics to produce laser emission at 13.6 and 2.1 nm. It is a first step towards compact X-ray lasers featuring higher repetition rate together with shorter wavelengths. This work is reported at paragraph II-3-b. The behavior of clusters irradiated by intense lasers has also been actively studied. The first experiments have been carried out with the femtosecond LUCA laser. A XUV emission in the 1-4 keV spectral range has been observed. These results have opened the way to the study of a high flux VUV source for nanolithography applications. The investigations are now carried on in the framework of the PREUVE project coordinated by the CEA/DTA/LETI Department. The first experiments started at the end of 1999.
I-2-b The LUCA Facility O. Gobert, P. Meynadier, D. Normand, M. Perdrix. Collaboration: J.P. Chambaret
LUCA is a versatile multi-beams tunable femtosecond laser facility of the DRECAM department, used by numerous research teams from the CEA, the CNRS, Universities, or foreign scientific organizations (see Figure 1), Experiments carried out with this system are very wide-ranging (e.g. femto-chemistry, solid state physics, laser-atoms, molecules or cluster interactions at high intensity).
42%
RECAM/LSj/DRECAM/SpCgj
7%
14% 11%
Figure I: Percentage of beam time allocation on the LUCA facility (year 2000)
18 Brief description of the facility : LUCA is based on a CPA Titanium-Sapphire laser with a 20 Hz repetition rate. This system is mainly composed of three parts: - Femtol is a two low-energy lines system, wavelength-tunable in the visible and ultraviolet. Its first line delivers 3mJ, 60fs pulses at 800 nm produced by a Ti:Sapphire chain. Its second line generates visible tunable pulses, with 50-60 fs pulse duration. They are obtained by amplification of a white light continuum in dye amplifier cells. The two lines are synchronized. With the use of frequency doubling and mixing schemes in nonlinear crystals, Femtol can deliver photons from the near IR (800nm) to the UV range (200nm) (see Figure 2). Thanks to the use of dyes, the pulse energies obtained in the visible (several hundred of microjoules) and in the near ultraviolet (several tens of microjoules) are among the highest values reported for these spectral ranges and pulse duration. - Femto2 is a high intensity Ti-Sapphire laser amplifier. It generates 100 mJ pulses at 800 nm with 60 fs pulse duration (FWHM). The peak power is approximately 2 TW with an intensity contrast of 105 at 2 ps. By frequency doubling in a KDP crystal, we obtain 20 mJ at 400 nm with a pulse duration of the order of 180 fs (see Figure 2). - a XUV source is available at the LUCA facility. It is based on the technique of high order harmonics generation of an intense laser pulse in a rare gas jet. It allows for the generation of highly coherent femtosecond pulses in the VUV-XUV range. Wavelengths as short as a few tens of nanometers are attainable (see Figure I). These characteristics show the great polyvalence of the LUCA facility: the experiments which can be performed range from pump-probe studies with low intensity, widely tunable fields, to high field physics at intensity up to 1017W/cm2. Such a versatility is very rare in Europe and, to our knowledge, is only achieved at LUCA and at the Lund Laser Center in Sweden.
UHI1CU 10" 1012 FEMTO2* High order FEMTO2J 1011 harmonics 1010 Femtol ~ 109 Femto2 I 108 UHI10 •FEMTO1: 107 6 o 10 High ortfer ^ 105 Harmonies • 104 Generation.^ 103 102
10° J //I.in,ml il.II.mil ii.l 10 100 200 300 400 500 600 700 800 Wavelength (nm)
Figure 2; Performances of the LUCA and UHI10 facilities in the different attainable spectral ranges
Recent developments : The LUCA facility, which came into service in 1993, is regularly upgraded. The latest important modification of the system was carried out in 1998 by the Thomson-BMI laser company. The objectives dealt with the reduction of the pulse duration (130 fs to 60 fs FWHM), together with an increase of the peak power (up to 2TW) and the improvement of the temporal contrast (105 at 2 ps). All these goals were reached. Furthermore, the upgrade has also led to an improvement of the reliability. Within the framework of these changes, the LUCA team had to adapt different related systems (systems to generate harmonics in
19 nonlinear crystals, dye amplifiers,...) to optimize their performance by taking advantage of LUCA's new characteristics. Another major development, carried out in 1999, was the modification of the laboratory in order to obtain 5 experimental sites instead of the 3 before. The reorganization of the laboratory was accompanied by the improvement of the spatial beam characteristics, thanks to a more systematic use of relay imaging and spatial filtering on temporally stretched beams. Other developments, such as a second compressor for Femto2 or the availability of continuously variable beam attenuators, have led to a more flexible use of the system. For example, it is now possible to use several beams with different wavelengths and temporal widths and with variable energy.
Operation : During 1998 and 1999, LUCA has been used with a reliability rate close to 100% (with the exception of the time used for development and the modifications of the laboratory). The usable beam time is over 7 hours per day. As well as maintaining the system, the operating team provides support for experimental groups in the following fields: optics, software development for data acquisition (labview) and the development of small mechanical systems.
Organization : An internal scientific committee defines the beam time allocation for each user teams. A user workshop is organized annually in order to give to the research teams the opportunity to debate about their scientific programs and main recent results. In 1999, we proposed that LUCA have access to the status of European Large Scale Facility with a beam time allocation for european users of 20% (SLIC project). We have applied to the CEE in the framework of the 5th PCRD but our project has been rejected and we plan to apply again this year.
Perspectives in the short and medium term : The technical perspectives for LUCA in the short and medium term are focused on: commissioning of new diagnostics. A SPIDER system is under development in order to measure the amplitude and phase of the laser electric field (in the spectral domain, thus also in the time domain). This project is linked to a collaboration with the LOA (Laboratoire d'Optique Appliqufe, Palaiseau, France). The spatial phase (wavefront) measurement is also a common project for UHI10 and LUCA. Having the ability to measure spectral and spatial phase and amplitude will eventually allow us to manipulate them (pulse shaping in temporal, spectral or spatial domain). improvement of the tunability. A new OP A system has to be developed to take full advantage of the new LUCA characteristics. New schemes, such as a NOPA (non collinear optical parametric amplifier) pumped at 400 ran could allow us to reach a continuous tunability in the visible and near UV range with pulse duration shorter than 60 fs. The development of an incoherent "intense" X ray photon source has already begun; it will extend to shorter wavelengths the spectral range covered by the high order harmonics XUV source.
Conclusion : Since the 1998 upgrade, the LUCA facility has been operating at its nominal performances with a very good reliability. Experiments carried out with this system have led to the publication of 21 articles in scientific journals and 5 PhD degrees since the last scientific council. If the planned developments are implemented, they will enable the team to continue to fully meet users' needs, to improve the polyvalence of the system and to provide much improved characterization of the laser beams.
I-2-c The UHI10 Laser Facility T. Auguste, M. Bougeard, E. Caprin, P. D'Oliveira, S. Dobosz, S. Hulin, P. Monot.
Since the end of 1997, the UHI10 laser (for Ultra High Intensity 10 TW) has delivered the intense ultrashort pulses used by the UHI team and their collaborators to study new X-Ray laser schemes and also to produce and characterize dense plasmas by means of spectral interferometry in the XUV range (see Sections II-4 and II-2-e).
Laser description : The UHI 10 facility is a Titanium-Sapphire laser based on the Chirped Pulse Amplification (CPA) technique. The intense pulses are generated in four steps. At the front end, a commercial
20 oscillator produces ultrashort (35 fs) low energy (3 nJ) pulses at a central wavelength of 795 run. These pulses are stretched up to a 300 ps duration by an aberration-free stretcher; they are then amplified in 4 amplification stages working at a 10 Hz repetition rate. After compression, performed in a vacuum chamber directly connected to the experiment chamber, the pulse duration is 70±10 fs and the peak power exceeds 10 TW. This is to our knowledge one of the 3 highest values reported in Europe for Titanium-Sapphire lasers. Due to the absence of aberration in the stretching process, the contrast ratio is approximately 105 at 2 ps from the maximum. Intensities in the 1019 W/cm2 range have been obtained with a 200 mm focal length off-axis parabola. The focused beam diameter is 3.5 times diffraction limited.
Recent developments : Since 1997, the UHI10 laser has been intensively used for the UHI group experiments, demonstrating a high reliability (availability rate above 90 %). During this period, it has been improved in several aspects. For instance, it is now possible to fire the laser in a single-shot mode with the monitoring of the pulse energy and duration for each shot. But the main modification is probably the addition of a second line (probe line) which delivers lower energy pulses (3 mJ, 70 fs) synchronized with the 10 TW pulses. The optical line used to bring the probe beam to the experiment chamber includes relay imaging optics in order to minimize the probe beam shot-to-shot displacements in the interaction area. A spatial filter can be inserted to improve the probe beam wavefront quality. In this configuration, the probe beam can be used as a source for the Mach-Zehnder interferometer which has been implanted inside the experiment chamber. The fringe quality at 400 nm (2n harmonic of the probe beam) is then better than a quarter of a fringe on a 15 mm diameter (see Figure 3). This interferometer has been successfully used to measure plasma density with a sub- picosecond temporal resolution. The probe line can also be set in a double-pulse mode (the delay between the pulses can then be varied between 50 and 450 fs) for XUV spectral interferometry experiments.
Figure 3: Interferogram of a Nitrogen plasma produced by the UHI 10 laser. The fringe quality demonstrates the low distortion of the probe beam wavefront
Prospects : During the next few years, one of our priorities will be to improve the focusing qualities of the 10 TW beam. To achieve this, we shall try to correct the beam wavefront distortions by inserting high flux spatial filters between the different amplifier stages. This requires first to define the filtering holes technology (material and geometry) and to estimate potential drawbacks of this method (decrease of output power, higher alignment sensitivity...). First experiments have been carried out during June 2000. The improvement of the temporal contrast is also absolutely necessary, especially for experiments on solid targets. Therefore, we shall perform joint experiments with the LOA (Laboratoire d'Optique Appliquee, ENSTA, Palaiseau). The objective of these experiments is to test the efficiency of several methods proposed in order to reach higher contrasts. We shall try, for instance, to insert between the oscillator and the stretcher, an amplification stage followed by a saturable absorber. By this means, the temporal contrast is expected to be improved by two or three orders of magnitude. The first experiments will take place at LOA in September.
21 Conclusion : Since its commissioning in 1997, the UHI10 laser has demonstrated a good level of performance and reliability. It allowed the UHI group to carry out its research programs involving laser-matter interaction at high intensity. The proposed developments will maintain the UHI 10 laser at a competitive level of performance.
I-2-d Production of coherent XUV by high order harmonics generation P. Agostini, P. Breger, B. Carre, M. Cheret, J.-F. Hergott, L. Le Deroff, H. Merdji, P.-M. Paul, P. Salieres. Collaborations: D. Joyeux, D. Phalippou, Ph. Zeitoun, E. Constant, E. Mevel, A. L'Huillier, C- G. Wahhtrom.
High-order harmonics generation in gases (HHG) has now gained the status of a usable XUV source, tunable from 100 to 10 nm, with rather unique properties. HHG is easy to produce using 2 to 50 mJ of the Femto2 laser output at 800 nm focused in the generating gas. The work on harmonics aims at i) characterizing the light emitted, ii) understanding the fundamental processes (e.g. phase matching) for improving the conversion efficiency, iii) developing applications. We briefly review the three points, which are developed in Section II- 2.
Characterization of the harmonics emission : Using a calibrated photodiode, we estimate that at 21 nm (H37) 10' photons/pulse are transmitted by an appropriate spectrally selective and focusing optics (multilayer mirror or Bragg-Fresnel lens). Spectral selection and off-axis focussing by a Bragg-Fresnel lens leads to a focal-spot size of 4±1 p (FW at 1/e2), i.e. intensity of ~1010 Wcm"2. Tight focussing already reveals the good beam quality, M2~2 [Le DeYoff 1998], implying high spatial coherence: at a first approximation, coherence properties of harmonics reflect those of the laser-driving field. At 60 nm (H13), we measure a degree of spatial coherence Yn ^ 0.5 in the full cross section of the beam, and Yn ^ 0.8 in a coherence cell representing 10% of the beam cross section [Le D6roff 2000]. A specific property of HHG is that one easily produces two mutually coherent sources from two distinct but mutually coherent laser beams, as illustrated in Figure 4.
Figure 4: Interferogram from two harmonics sources at 40 nm separated in space by 100 fim; a uniform contrast of more than 75% is achieved.
Optimization of conversion efficiency : Optimizing HHG means finding the best compromise between high non-linear polarization (high density, high intensity), large emitting volume, good phase matching, limited ionization by the laser and negligible reabsorption of the harmonics. We have checked optimal conditions of atomic density and medium length in various geometries of the medium (gas jet, gas filled hollow-core fiber and cell).
Applications of ultra-short XUV : Applications of HHG have represented about 60% of the run time in 1998-2000. Pump+probe time-resolved studies of subpicosecond dynamics, furthermore implying coherent XUV, make full use of HHG properties. The two main applications developed until now, i) the time-resolved measurement of the electron density in a laser-produced plasma [Salieres 1999] and ii) the study of the relaxation of electrons excited in the conduction band of silica [Quere" 2000], are detailed in Section II-2. Further applications to time-resolved interferometry diagnostics of over-critical plasmas and reflective surfaces are planned for the near future. Applications to dynamical studies in molecular physics are also envisaged.
22 I-2-e Selected references LeDerofTL., Salieres P., Carr6B., Opt. Lett. 23. 1544 (1998). Le Deroff L., SaliSres P., Carre" B., Joyeux D.. Phalippou D., Phys. Rev. A 61, 043802 (2000). Quere" F., Guizard S., Petite G., Martin Ph., Merdji H., Carre" B., Hergott J.-F., Le Deroff L., Phys. Rev. B 61, 9883 (2000). Salieres P., Le Deroff L., Auj;uste T., Monot P., D'Oliveira P., Campo D., Hergott J.-F., Merdji H., Carr6 B., Phys. Rev. Lett. 83, 5483 (1999).
23 1-3 Synchrotron sources and Free Electron Lasers. Permanent research staff: M.E. Couprie, D. Garzella, P. Morin, L. Nation PhD students: D. Nutarelli, R. Roux, M. Hirsch. Post-doctoral position: E. Renault, G. De Ninno Collaborations: C. Alcaraz, P. Dumas, O. Dutuit, A. Taleb-Ibrahimi (Laboratoire pour l'Utilisation du Rayonnement Electromagne'tique, Orsay), M. Billardon, C. Boccara (Ecole Supe"rieure de Physique et Chimie Industrielles, Paris), M. Drescher (University of Bielefeld, Germany), M. Marsi (ELETTRA, Trieste, Italy), K. Ito (KEK, Tsukuba, Japan), R. Thissen (Laboratoire de Chimie Physique, University Paris XI, Orsay)
I-3-a Introduction
SPAM teams are involved in source development programs carried out at the LURE (Orsay), generally in collaboration with researchers from the CNRS or the Orsay University. Beside the development of the SU5 beam-line and of the Super-ACO Free Electron Laser, which are described below, the SPAM is also very interested in the so-called "3rd generation" synchrotron machines, sources delivering high brilliance VUV and XUV photon beams. Note that the SU5 beam line has been designed in order to be transferred onto the 3rd generation synchrotron source SOLEEL. One of us (P. Morin) has been involved as a co-chair of the experimental program of the SOLEIL detailed project. This includes for instance, beamlines organization, specifications of the experiments and general requirements of the scientific program. Several working groups as well as numerous workshops have been organized to achieve these tasks.
I-3-b SU5: a VUV high resolution beamline with variable polarization L. Nahon Collaboration: C. Alcaraz M. Drescher, O. Dutuit, K. Ito, R. Thissen
The SU5 high-resolution beamline of Super- ACO (LURE) is primarily devoted to the study, in the VUV range, of very high-resolution spectroscopy and of photon-induced dynamics on diluted systems such as cold molecules, molecular and metallic aggregates, radicals and laser-excited species. A second scientific case deals with the study of anisotropic systems such as laser-aligned species, molecules adsorbed on surfaces, chiral molecules or magnetic systems, via linear and circular-dichroism experiments. In order of achieve such a dual scientific program, the technical requirements are the following: (i) the possibility of generating "exotic polarizations"; (ii) a high spectral purity; (iii) an ultimate resolving power in the 100000 range between 5 and 30 eV with rather high flux, allowing, for instance, ro-vibronic resolution on small molecules.
Generation and control of "exotic" polarization : In order to achieve this goal, we have conceived, built and commissioned the first 10 period electromagnetic Onuki-type [Onuki 1986] crossed undulator, called OPHELIE [Nahon 1997], in which 3 parameters can be tuned: the vertical and horizontal magnetic fields Bv and BH, and their relative phase <|>. After an intensive magnetic measurement campaign, the on-beam commissioning has been successful in the DC mode, allowing the modification of any settings of the undulator with a typical time constant of one minute between two configurations. We have also shown that the fundamental radiation can be easily tuned from 5 to 22 eV, and that the whole insertion has a high vertical/horizontal symmetry [Nahon 2000]. Besides, we have been able to produce and measure, for the first time in the VUV range, a complete set of polarization ellipses including of course the linear (in any direction) and circular cases. On a quantitative point of view the linear polarization degree is higher than 98 % in the linear polarization configurations, while in the circular polarization configuration, the circular polarization degree is higher than 98 % (assuming an unpolarized contribution smaller than 1 % as in the linear case) [Alcaraz 1999].
Spectral purity : The high spectral purity is provided by a high-pressure differentially-pumped gas cell, which absorbs any photon whose energy is located above the ionization potential of the filling rare gas, providing an harmonic-free radiation. Attenuation factors higher than 200000 with 1 torr of argon have been
24 directly measured by ion yield experiments. They are in good agreement with numerical simulations taking into account the actual shape of the gas cell with its conductance capillaries [Mercier, 2000].
Resolving power : A specific monochromator has been designed in order to achieve the resolving power specification. The optical design [Nahon 1998] is centered around a 6.65 m normal incidence Eagle off-plane monocliromator, illuminated by an astigmatic pre-focusing system, and equipped with two gratings: a 2400 I/mm and a 4300 I/mm. The spectral resolution has been measured by collecting the ions produced by spin- 5 2 2 orbit autoinization between the two np ( P3/2) et ( P1/2) thresholds of 3 rare gases: Ne, Ar and Xe. The results are very satisfying: at 21.6 eV (Ne) the ultimate resolution is 0.184 meV (R = e/Ae= 117000) (see Figure 5) which is the best result ever obtained at this energy (previous world record: 70000 at the ALS). At 15.8 eV (Ar) the ultimate raw bandwidth is 0.119 meV (R = 133000), which gives an instrumental width of 0.076 meV (R=208000), obtained by deconvolving 0.054 meV due to the natural width of the 13s' level. On the whole VUV range, a resolving power higher than 105 can thus be obtained with typical flux ranging from 109 to 1010 ph/sec in a 1/50000 bandwidth. These very good results are due to the intensive work regarding the optical and mechanical design and the minimization of vibration, as well as the quality of the gratings.
Aufoionization spectrum of neon (4300 I/mm grating)
20x10 Slits 20 urn : FWHM (raw) = 0.22 rneV R- 97000
-62
O
o
21.56 21,58 21.60 21.62 21 64 21.66 Photon energy (eV)
Figure 5: Autoionization spectrum of neon (43001/mm grating), measured with 20 |j.m slits (10 \im slits in insert).
Conclusion and prospects : The commissioning of the SU5 beamline has demonstrated that its performances are in accordance with the initial specifications. SU5 has accommodated its first users in February 2000. Future efforts will be directed towards the on-beam commissioning of the undulator in the AC mode, with a possible helicity switching frequency in the 0.1 - 0.5 Hz range, together with the commissioning of a new home-made VUV polarimeter, which should provide an in situ, under vacuum, polarization analysis of the synchrotron light right upstream of the sample location.
25 I-3-c The UV Free Electron Lasers and their applications M. E. Couprie, G. De Ninno, D. Garzella, M. Hirsch, L. Nahon, D. Nutarelli, E. Renault, R. Roux. Collaborations: M. Billardon, C. Boccara, M. Marsi, A. Taleb-Ibrahimi, P. Dumas
The team has been actively involved in the development of Ultraviolet Free Electron Lasers. These activities include also systematic studies concerning the cavity mirrors together with theoretical developments on the stability and dynamics of the FEL. In parallel, the application program of the Super-ACO FEL has been developed in new directions. The experiment relevant to biology is reported in Section III-5-b. The activities at ELETTRA as well as the theoretical developments and the optics studies are developed in the framework of two European networks in which the team is actively involved.
Design and improvement of UV FEL sources :
Super-ACO FEL : The team has carried on the development of the Super-ACO FEL which is now routinely operated at 800 MeV with two radio-frequency cavities on Super-ACO. With this new configuration, the gain at 350 nm can reach 2.5% (instead of 1.5% with only one cavity) and the FEL output power for the users has been increased up to 300 mW. The tunability has been doubled and is now of 20 nm. Owing to a longitudinal feedback system and specific machine adjustments, the stability has been improved, leading to the suppression of low frequency intensity modulation and the reduction of the temporal jitter between the FEL and RS pulses (see Figure 6). Moreover, the natural FEL pulse duration is typically of the order of 30-40 ps, with a laser line bandwidth 0.6 A, but in presence of the longitudinal feedback system, the FEL can even operate much closer to the Fourier limit (12 ps, 0.3 A) (see Figure 6). More recently, the FEL operation has been pushed down to shorter wavelengths and a power of about 10 mW has been obtained at 300 nm [Nutarelli 2000]. The improvement of the Super-ACO FEL will be carried on in order to reproduce at 300 nm the level of power and stability demonstrated at 350 nm.
ELETTRA FEL: The team has also been deeply involved in the design and construction of the ELETTRA FEL, built on the Italian national synchrotron radiation facility located at Trieste. The FEL is operated at 1 GeV, an energy lower than the nominal energy of ELETTRA, with a 5 m long helical optical klystron. The optical cavity allows the mirrors to be changed under vacuum. The theoretical gain value in the UV is greater than 20%. The first FEL lasing was achieved in January 2000, at 350 nm, with 20 mW; in May 2000, the FEL was operated at 220 nm with 10 mW. Thanks to the optimization of the interaction between the FEL and the electron bunches, powers of several watts are expected below 300 nm together with the possibility of operating at wavelengths below 200 nm.
SOLEIL FEL : The team continued the optimization of the SOLEIL FEL project. The design of the very long straight section devoted to the FEL (14 m) and the high quality of the electron beam led to remarkable properties for the FEL oscillation: few picoseconds pulse duration, several Watts of average power, high brilliance...Coherent harmonics of the SOLEIL FEL will be generated down to 30 nm with powers in the mW range. One should underline that the SOLEIL FEL source is still unique in its planned performances, being the only FEL integrated at the origin in the design of a 3rd generation synchrotron; in our opinion, its commissioning should open new scientific opportunities. Finally, we also performed calculations for an alternative scheme using an external ultrashort laser (Ti:Sa) to generate coherent harmonics; this set-up extends the versatility of the proposed SOLEIL FEL by giving access to peak powers approximately 10 times higher (compared to the FEL peak power) with subpicosecond pulse duration and a kHz repetition rate.
26 800 PS
3 ex FBoff 100 ms £ 800 ps
LU U. FBon 100 rvB 3S3AA time Figure 6: improvement of the Super-ACO FEL operation with the longitudinal feedback (FB) system. On the left: stabilization of the FEL micropulse measured with a double sweep streak camera. On the right: reduction of the FEL line
Cavity mirrors development: The design and improvement of the UV FEL sources at super-ACO and ELETTRA have required the development of cavity mirrors exhibiting a very high reflectivity in the UV together with a good resistance to the synchrotron flux. To achieve this dual task at wavelengths below 350 nm, we have performed R&D studies concentrated on the testing of new coatings and materials. Multilayer coatings at 300 nm and 250 nm with combination of binary oxides (i.e. HfO,/SiO2, Ta2C>5/Si0,, Al2O3/SiO2) and fluoride monolayers have been characterized. This has been possible thanks to the upgrade of the optical characterization system, allowing measurements at various wavelengths down to 229 nm, and to the setting up of a new optical-absorption bench, based on the "Mirage effect", which has a sensitivity of few tens of ppm over the whole accessed spectral range.
FEL stability and dynamics simulation : The FEL stability being of primary importance for the applications, our team has carried out simulations in order to increase our understanding of the FEL stability and dynamics. We recently proposed a new model taking into account the local interaction of the FEL pulse in the electronic distribution, considering only the small fraction of the electrons which effectively interact with the FEL electric field, which is ten to twenty times narrower than the electrons bunch. Simulations show that a hole burning effect may occur, and clearly foresee a modification of the shape of the electron bunch. After several hundreds of (is, the electron diffusion brings back the electronic distribution to its natural shape. Experiments with the Super-ACO FEL operated in the Q-switched mode are in good agreement with simulations.
The scientific program in surface, solid states and molecular physics :
The aipplication program has been intensively developed during the last couple of years, taking advantage of the improved performances of the FEL, mainly in terms of extracted power and stability. The synchronization between the FEL and the SR is used in order to perform time-resolved two-color pump/probe experiments, in which the FEL produces excited states whose relaxation dynamics is probed by the SR.
Applications in surface sciences : During the last years, we have carried on experiments in surface sciences in collaboration with M. Marsi (ELETTRA, Trieste, Italy) and A. Taleb (LURE, Orsay). The FEL was used to produce transient photo-carriers at semi-conductor interfaces. The charge dynamics was then probed by core level photoemission with the SR. After bare Si interfaces, we studied the transient regime of the charge distribution after UV photoexcitation at the Si/SiO2 interface, a system of great technological relevance for micro-electronics. The data show that electrons generated in the Si substrate can accumulate at the surface of the oxide layer, strongly affecting the electric field at the interface [Marsi 2000]. For n-type silicon, this effect can lead to an enhancement of the curvature of the bands, rather than to the expected flattening due to the Surface Photovoltage (SPV), as revealed by the unexpected reverse direction in the core photoemission peak shift. The characteristic decay time of this vacuum transient charging at the surface of the oxide layer depends markedly on its thickness, ranging from sub-ns to us. Our results indicate that for about 12 A oxide thickness, it is comparable to the typical excess carrier bulk recombination time in silicon (about 10 -100 ns). In the near future, we plan to investigate the direct two-photon photoemission in order to probe the empty states of the conduction band in semi-conductors. Preliminary data show that such an experiment is feasible in terms of overall photon flux.
27 Applications in material sciences and molecular physics : A new kind of experimental set-up has been developed. It couples the Super-ACO FEL with the white light continuum of the SR in the IR range (2 -20 u.m) in order to measure the transient absorption of SR on FEL-excited samples. The diagnostics consist of a Fourier-transform spectrometer associated with a microscope, the combination of these instruments allowing the collection of 3D data, in the temporal, spectral and spatial domains. Such an IR/UV combination is potentially extremely fruitful since it might bring information on the possible coupling at the molecular level between the electronic and nuclear motions. Applications range from the study of photo-conductivity of large- gap semi-conductors, to chemical reactions involving molecules adsorbed on thin films, as well as gas-phase molecular dynamics. As a first experiment, in collaboration with P. Dumas (LURE), we monitored via IR micro-spectroscopy, the time evolution, on the minute timescale, of a single mineral particle (kaolinite) under UV-FEL irradiation. The data show a strong and selective modification of the IR bands corresponding to the external-OH stretching modes of the sample [Nahon 1999]. With these encouraging results, fast dynamics, on the ns timescale, should be investigated in the near future.
Production of highly collimated v ray beams :
We have generated an highly collimated y ray beam by Compton backscattering interaction between the UV FEL and an additional bunch of relativistic positrons stored in the Super ACO cavity. This experimental set- up is very favorable as the laser beam and the electron bunch are naturally collinear and synchronized. The spectrum of the y beam was characterized by means of different detectors (Nal, Germanium,...); the y photon energy is centered at 35 MeV (see Figure 7). We have observed that the 35 MeV photons are emitted on axis, while photons with lower energy are produced off-axis [Couprie 1999]. The y ray yield was also directly evaluated through the lifetime measurement of the additional bunch: at the Super ACO nominal energy (800 MeV), 10^ photons/s are produced in the 6 mm diameter collimated beam. These promising results suggest that this set-up may be used as a potential gamma source.
10 20 30 40 Energie du photon (MeV)
Figure 7: Energy spectrum of the gamma ray beam measured with a Nal detector at 10 mfrom the collision point
28 I-3-d Selected references :
Alcaraz C, Thissen R., Compin M., Jolly A., Drecher M., Nahon L.( Proc. SPIE 3773, 250 (1999).
Couprie M.E., Nutarelli D., Roux R., Visentin B., Naxion L., Bakker R., Delboulbe" A., Billardon M., J. Phys. B (At. Mol. Opt. Phys.) 32, 5657 (1999)
Marsi M., Belkou R., Grupp C, Panacione G., Taleb-Ibrahimi A., Nahon L., Garzella D., Nutarelli D., Renault E., Roux R., Couprie M.E., Billardon ML, Phys. Rev. B 61, 5070 (2000).
Mercier B., Compin M, Prevost C, Bellec G., Thissen R., Dutuit O., Nahon L., , J. Vac. Sci. Technol. A (2000) (in press).
Nahon L., Corlier M., Peaupardin P., Marteau F., Marcouille" O., Brunelle P., Alcaraz C, Thiry P., Nucl. Instr. Meth. A 396, 237 (1997).
Nahon L., Lagarde B., PolackF., Alcaraz C, Dutuit O., Vervloet M., Ito K., Nucl. Instr. Meth. A 404, 418 (1998).
Nahon L., Renault E., Couprie M.E., Nutarelli D., Garzella D., Polack F., Carr G. L., Williams G., Dumas P., Proc. SPIE 3775, 145 (1999).
Nahon L., Thissen R., Alcaraz C, Corlier M., Peaupardin P., Marteau F., Marcouille" O., Brunelle P., Nucl. Instr. Meth. A 447, 569 (2000).
Nutarelli D., Garzella D., Renault E., Nahon L., Couprie M.E., Nucl. Instr. Meth. A (2000) (in press).
Onuki H., Nucl. Instr. Meth. A 246, 94 (1986).
29 II MATTER UNDER EXTREME CONDITIONS
III GENERAL PRESENTATION 33
II-2 Production of coherent XUV light by harmonics generation 34
II-2-a Introduction 34 II-2-b Investigations of phase-matching in harmonics generation 35 Optimal phase-matching in an absorbing medium Harmonic generation in a self-guided femtosecond pulse II-2-c Coherence properties of high order harmonics 36 Spatial coherence of the harmonics emission Mutual coherence of two harmonics sources II-2-d Applications of ultra-short coherent XUV light to time-resolved interferometry 37 II-2-e Measurements of ultra-fast electron relaxation on a-SiO2 using harmonics 39 II-2-f Conclusions - Perspectives 40 II-2-g Selected references 41
II-3 Molecules and clusters in strong fields 42
H-3-a Introduction 42 II-3-b Molecular multi-ionization and Coulomb explosion 43 Non-sequential double and multiple ionization Coulomb explosion: theory vs. experiments Excited transient multi -charged molecules Perspectives II-3-c Highly charged ions from rare gas and metal clusters in intense laser fields 45 II-3-d XUV and fast ion emission from a laser generated plasma in a liquid jet target 45 II-3-e X-ray emission from fast expanding molecular cluster plasma 46 II- 3-f Theoretical description of cluster in strong laser field 47 Monte Carlo particle dynamics simulations of the rare gas cluster explosion in a strong laser field Cluster explosion in an intense laser field: Thomas-Fermi model II-3-g Conclusions - Perspectives 49 II-3-h Selected references 49
II-4 Ultra-short non LTE plasmas produced by Optical Field Ionization 50
II-4-a Introduction 50 II-4-b Towards an X-ray laser using short-duration, high-intensity pulses 50 Femtosecond driven X-ray laser principle Characterization of OFI produced nitrogen plasma as a lasing medium Neutral and electronic density Temperature and peak intensity Interaction length II-4-c Acceleration of charged particles in dense plasmas 52 Energetic ions Supra-thermal electrons II-4-d Conclusions - Perspectives 53 II-4-e Selected references 54
31 II-5 High energy density matter and atomic physics 55
II-5-a Introduction 55 II-5-b Development of the SCO opacity code 55 II-5-c Collaboration with the LULI and PHEBUS experimental teams 56 II-5-d Linear response theory for atoms in plasma 57 II-5-e Hydrodynamics experiment on the Ph6bus laser 57 II-5-f Spectroscopy of two-electron atoms and multi-charged ions 58 II-5-g Multicharged ion-atom and ion-molecule collisions 59 II-5-h Conclusions - Perspectives 59 II-5-i Selected references 60
32 II MATTER UNDER EXTREME CONDITIONS
HI GENERAL PRESENTATION
For more than twenty years, studies of atoms and molecules in strong laser fields have been a major topic of research at SPAM. They have evolved within the past ten years taking advantage of the ultra-short pulse, terawatt laser facilities installed at FJRECAM - see Section 1-2. From the studies of isolated molecules in strong field to those of laser-produced plasma, the work on matter-strong field interaction in the Group retains its character of fundamental research, but it marks an increasing concern for applications. Furthermore, most of the studies show close or indirect connections with the physics that will be worked out by the forthcoming high power laser facilities of ithe CEA, successively the Ligne d'Migration Laser (LIL) and Laser MegaJoule (LMJ). They contribute through theoretical work, model experiments or development of diagnostics, to the major and long-term programs of the CEA. The Group is composed of 19 permanent physicists and technicians, an approximately constant number of 7 doctorate students and 5 post-doctorate collaborators. A large part of the activity concerns studies of the dynamics of atoms, molecules and clusters at laser intensities of 1014 Wcm"2 to 1019 Wcm"2, and time scale of lOOfs. At these intensities, the interaction can be described in the context of the strong field approximation: the dynamics does not depend significantly on the energy level structure of the system which reduces to the ground and continuum states; the system is very rapidly ionized through tunneling or Optical Field Ionization (OFI); the electron dynamics is that of a free electron in a strong driving field, the conditions for a bound state playing only the role of boundary conditions of the motion. In the final stage of the interaction with intense ultra-short laser pulse, the system is ionized to highly charged states; the strong field studies make therefore explicit or implicit reference to the physics of plasmas which are out of Local Thermodynamical Equilibrium (non-LTE plasmas). Strong field studies in the Group include the following themes: 1. Production of coherent XUV light by harmonic generation and Applications. The team maintains expertise in both theoretical and experimental investigation of far UV to soft X-ray (XUV) production through harmonics generation. Applications of the ultra-short coherent XUV light are developed in plasma physics and surface physics. 2. Polyatomic molecules and clusters in strong field. Studies of ionization and Coulomb explosion of multi-charged small motecules are pursued towards an almost complete description of the interaction. In the case of large size clusters, production of XUV light, ejection of highly charged energetic ions are studied with both fundamental and applied purposes. 3. Ultra-short non-LTE plasmas produced by Optical Field Ionization. Application to an X ray-laser scheme is developed, which requires a detailed characterization of the OFI plasma. Actually, plasma physics is now a topic of major importance at SPAM. Besides non LTE plasmas, high-energy dense LTE plasmas, produced by high power nanosecond lasers, are also considered, first from a theoretical point of view. Also theoretical, studies on multi-charged ions naturally find place in this context. A fourth theme is therefore: 4. High-energy LTE plasma and atomic physics in plasmas. This activity is explicitly connected to the present and future programs on high power laser facilities (LULI, LIL and LMJ).
The report follows the above division. At present, many links and exchanges exist between the different teams, experimentalists and theoreticians, who combine their expertise without renouncing their specificity. The teams are also involved in several collaborations with laboratories inside or outside the CEA. Among registered collaborations in the 1998-2000 period, the teams are participating in 3 Training and Mobility Research Networks, 2 Groupes de Recherche, 4 Laboratoires de Recherche Correspondants partnerships, 1 research contract on SBLVA isotope-separation process.
33 П-2 Production of coherent XUV light by harmonics generation Permanent research and technical staff: P. Agostini, M. Bougeard. P. Breger, E. Caprin, B. Carré, M. Chéret, Y. Gontier, P. Salières PhD students: L. Le Déroff, J.-F. Hergott, P.-M. Paul, P. Villain Post-doctoral positions: D. Garzella, H. Merdji Undergraduate students: O. Chiappa. С. Hubert Collaborations: D. Joyeux. D. Phalippou (Institut d'Optique Théorique et Appliquée, Orsay), Ph. Zeitoun (Laboratoire de Spectroscopie Atomique et Ionique, Université Paris XI, Orsay), E. Constant, E. Mével, F. Salin (Centre d'Etudes des Lasers Intenses et Applications, Université de Bordeaux), D. Descamps. A. L'Huillier, C.-G. Wahlström (Lund Institute of Technology, Sweden), M. Lewenstein (Hannover Universität, Germany), L. Di Mauro (Brookhaven National Laboratory, USA), H. G. Müller (FOM, Amsterdam, The Netherlands), F. Quéré, S. Guizard, P. Martin, G. Petite (CEA/DSM/DRECAM/Service de Recherche sur les Surfaces et l'Irradiation de la Matière), C. Dorrer, С Leblanc, H. R. Lange, A. Chiron, J.-F. Ripoche. A. Mysyrowicz (Laboratoire d'Optique Appliquée, ENSTA, Palaiseau)
П-2-а Introduction
High-order harmonies generation in gases (HHG) is now recognized as a very interesting source in the XUV range, typically from 100 to 10 run but even down to the water window at 3 ran [Spielmann 1997]. HHG is relatively easy to produce under conditions of ultra-short pulses (x < 100 fs) of "intermediate" intensity (I < 10b Wem"2), with either the LUC A and UHI lasers in Saclay, or equivalent laser facilities available to the SPAM physicists via collaborations (LOA-ENSTA Palaiseau, Lund Laser Center, CELIA Bordeaux). Harmonic light gets most of its unique characteristics from the fact that HHG is a coherent process tightly driven by the laser field. In addition to the ultra-short pulse duration and high repetition rate, the temporal and spatial coherence, regular wave front, or mutual coherence of two harmonic sources originate in the corresponding properties of the driving laser. The harmonic emission also reflects the particular dynamics of the atomic electron in the strong laser field and the macroscopic conditions of generation/propagation - i.e. phase matching - in the medium. Consequently, HHG critically depends on the generation parameters. As those of most of the groups involved in HHG, our studies serve the purpose of i) investigating fundamental aspects of the process and optimizing generation efficiency by a finer control of phase-matching in different conditions, ii) characterizing the remarkable properties - e.g. ultrashort pulse duration through cross- correlation measurements [Bouhal 1998] or the coherence - of harmonic emission, and iii) developing applications of ultra-short, coherent XUV light. As a significant fundamental contribution (collab. Brookhaven National Laboratory), the team has investigated for the first time high harmonic generation from a mid-infrared laser (À=3-4 um) in alkali atoms [Sheehy 1999]. This makes it possible to study non-perturbative interactions in a broad class of atomic systems with small binding energies. Experimentally, harmonic generation at long wavelength spans the visible to near UV range, so that well established techniques for complete characterization of amplitude and phase of the harmonic field are applicable. Two main applications to time-resolved studies of the pump+probe type have been developed so far. First for plasma diagnostic, we use two mutually coherent harmonic sources, either separated in space or in time, to probe the electron density in a laser-produced plasma on a solid target (collab. Lund) and a gaseous target. In solid state physics, we have probed, using photoelectron spectroscopy (collab. SRSIM), the relaxation of electrons excited in the conduction band of a dielectric material. Each type of study needs efficient XUV optics capable of reflecting, selecting and focusing the light without degrading its properties. Therefore, we have also used harmonics to qualify XUV optics such as multilayer mirror or Bragg-Fresnel lens [Le Déroff 1998]. Although mainly experimental, the work on field-driven processes at SPAM includes theoretical simulations of HHG, as well as atom-field correlation studies [Gontier 1999]. Besides the atom-field topic, a PhD thesis theoretical work continues the collaboration with the group of M. Lewenstein, now at Hannover Universität [Villain 2000]. The technical staff (2 persons) is common to the four teams of the Group.
34 II-2-b Investigations of phase-matching in harmonics generation P. Agostini, M. Bougeard, P. Breger, E. Caprin, D. Garzella, J.-F. Hergott, H. Merdji, B. Carre, P. Salieres. Collaboration: E. Constant, E. Mevel, C. Dorrer, C. Leblanc, F. Salin, H. R. Lange, A. Chiron, J.-F Ripoche, A. Mysyrowicz
The efficiency of harmonic generation results from the interplay of several parameters. Schematically, one should combine the highest non linear polarization in a large volume with the phase-matching conditions between non linear polarization and the harmonic field, together with limited ionization and low absorption of the harmonic field in the medium. It is now well established that in the strong-field regime, non linear polarization at frequency qco shows an intrinsic, intensity-dependent phase
Optimal phase-matching in sin absorbing medium Both a simple analytical model and numerical simulations show that optimal HHG in an absorbing medium characterized by an absorption length Labs can be obtained close to the conditions Lmed > 3Labs and Lcoh > K 5Labs, where Lmeci is the medium length, Lcoh - the coherence length. As a rule, this results, for a given Ak medium length, in an optimal atomic density. We have checked experimentally the existence of this optimal pressure for low to higher harmonics generated in rare gases. In Figure 1, the optimal pressure for the 15th harmonic in Xe is, as expected, lower in the long hollow-core fiber medium than in the jet. Furthermore, a more uniform distribution of laser phase and intensity in the fiber acting as a wave guide leads to better phase matching and higher HHG efficiency. The same feature of an optimal pressure is measured in argon in Figure 1, whereas Figure 2 illustrates the change in the phase matching when increasing the pressure from P 1.6x10" ArH19 i— Xe(jet) •—Xe (fiber) — Arx10 (fiber) xi 0.4- I CO I 0.2- o c O.0[ 0.0 100 200 300 400 -3 0 3 Backing pressure (mbar) divergence (mradj Figure 1: Number of photons per pulse for H15 Figure 2: Divergence of the 19th harmonic far-field generated in Xe (square) and Ar (circle) in a 4 cm- illustrating the change in phase matching from long fiber, in Xe in a 800 fimjet. P 35 Harmonic generation in a self-guided femtosecond pulse The interplay between coherence and medium lengths, in the case of weak absorption, can be illustrated in various systems. In the following example, we have generated high harmonics in a rare gas cell of variable length, using ultra-short self-guided laser pulses propagating in air [Lange 1998] (collab. SPAM/LOA). Intensity of approximately 10lj Wcm2 is reached in the filament, sufficient to produce the lowest order 3rd to 9th harmonics. Characteristic Maker fringes are observed in Figure 3 when the gas pressure is varied : the coherence length Lcoh decreases with pressure leading to successive maxima for the values Lmed /(2n+l), where n is an integer. It indicates that non linear polarization at frequency 3co and the harmonic field remain locked in phase (constructively or destructively) over the medium length (35 mm). By inserting into the cell a silica thin plate, which changes the fundamental phase by n (without affecting significantly the 3rd harmonic field), we can rephase the two waves as shown by the change in the pressure dependence in Figure 3. 16- m 1.4- L • Figure 3: Third harmonic signal produced in Xe by 1 self-guided laser pulse as a function of gas pressure I °" \ A ; A in a 35 mm cell (open circle); rephasing of laser and " 08- f Vp ;°' b / / i ' / V harmonic fields by mean of thin silica placed in the IUI I i / \I ° \ = 06- / • middle of the cell (solid square). l 6 \ I \ 0! \ j '•• 1 0 2- I \ 0 0- W \-J 1 \ " 5C 100 150 200 250 300 350 pressure (mbar) II-2-c Coherence properties of high order harmonics L. Le Derojf, J.-F. Hergott, H. Merdji, B. Carre, P. Salieres Collaboration: D. Joyeux, D. Phalippou As already mentioned, HHG gets its coherence properties from the laser driving field. Under conditions close to phase matching, the harmonic phase is, at a first approximation, determined everywhere in space and time by the phase and intensity of the laser. This is the basis for the properties of intrinsic, spatial and temporal coherence of the harmonic field. However, for a greater understanding, one should consider that the coherence of the laser field itself (the non linear polarization) is affected by the onset of any time- and space-dependent process in the generating medium, such as ionization and subsequent electronic dispersion. Moreover, one should account for the intensity-dependent dipole phase <£>q in the harmonic field, which can also degrade both the spatial and temporal coherence of the harmonic emission. As a result, the coherence properties are critically dependent on the generation parameters [Salieres 1998,1999a, Le Deroff 2000a]. Even in the case of a reduced intrinsic coherence of a single harmonic source, the key feature of a laser-driven process enables two mutually coherent harmonic sources to be produced. This remarkable property is highly specific to the HHG. We have successfully used it to perform interferometric applications of the harmonic light, developed in Section II-2-d. Spatial coherence of the harmonic emission We have measured the complex degree of spatial coherence for harmonics 13th and 15th generated in a Xe gas jet, using a Fresnel's mirrors interferometer [Le DeYoff 2000b]. With this arrangement, we can build a 2D- map of the coherence throughout the transverse cross-section of the harmonic beam, for a given separation d between the interfering rays, at distance L~l m from the source. For the optimal set of phase-matching parameters, a high degree yn (modulus), yn ^0.5, is found for separation d up to the full diameter of the harmonic beam (-3 mm): it means that the coherent flux is almost equal to the total flux. Because it reflects the intrinsic coherence of the harmonic source, the yn degree is much larger than that obtained in similar conditions from a purely incoherent source (yn ~ 0.02 for d=3 mm), the latter being that of most XUV sources. Figure 4 shows the variation of the yn degree as a function of the jet-to-focus relative position, for 36 distance d=2 mm between the interfering rays. The decrease of yn when moving the focus from outside (lzl>2 cm) to inside the jet is due to the high laser intensity and subsequent ionization in the generating medium, resulting in large space- and time-dependent factors in the harmonic field phase and reduced coherence. Figure 4: The y12 degree of spatial coherence as a function of the jet-to-focus relative position, for distance d-2 mm. -4-2 0 2 4 6 8 10 jet/focus position (cm) Mutual coherence of two harmonic sources Two mutually coherent harmonic sources can be produced from two mutually coherent laser pulses, either separated in space or in time. The former scheme corresponds to Young's two-slit and has been demonstrated for high harmonics in the Lund group [Zerne 1997]. The latter scheme is known as frequency-domain interferometry and currently used in the visible [Colombeau 1990]. We have demonstrated that the technique can be extended to the XUV using harmonics [Salieres 1999c]. Two harmonic pulses separated by a delay x are produced at the same place in the medium by two delayed but spatially superimposed and otherwise identical laser pulses. After diffraction on a spectrally dispersive optics (grating), the two pulses overlap in time and interfere in the frequency domain. Figure 5 shows the interference pattern measured in the spectral plane for 11th , 15th and 19th harmonic pulses delayed by £=120 fs. The large contrast indicates that, when ionization by the first laser pulse is not too high, the two harmonic sources are mutually coherent. Conversely, the study of the contrast as a function of the generation parameters gives information on the dynamics of ionization in the medium. 1.0 -1 1 3 -3 -1 1 3 -3 -1 1 AX (A) AX. (A) AX (A) Figure 5: Experimental spectra of harmonics 11 (a), 15 (b) and 19 (c) generated by two laser pulses delayed by v=120 fs and focused at 2x1014 Wcm'2 in argon. The spectral profile of one single pulse is modulated with the period A! = — CT II-2-d Applications of ultra-short coherent XUV light to time-resolved interferometry P. Salieres, P. Monot, P. D'Oliveira, T. Auguste, H. Merdji, J.-F. Hergott, L. Le Deroff, B. Carre Collaboration: D. Descamps, A. L'Huillier, C.-G. Wahlstrom The unprecedented coherence properties of harmonic radiation open the way to ultra-short (subpicosecond) time-resolved XUV interferornetry. Furthermore, HHG brings to the technique the major improvements of tunability, compactness and simplicity. Particularly interesting is the diagnostic of dense plasmas, since they refract (by the steep density gradients), absorb and reflect (above the critical density) the long wavelengths. So 37 far, only X-ray lasers have been used to probe plasmas by XUV interferometry. We have performed two interferometry experiments using two mutually coherent harmonic sources, separated either in space or in time. In the first experiment in collaboration with the Lund group, we generated two spatially-separated phase- locked harmonic sources by focusing the two-fold split laser beam at different locations in a gas jet. The plasma was created on the path of one harmonic beam by irradiating an aluminum target with a 50 mJ-300 ps laser pulse, the second beam being the reference. The interference fringes observed in the far-field when the beams overlap are locally shifted allowing the determination of electronic densities as high as 2.10,20 electrons/cm' [Descamps 2000] - see also Section I-2-d. (a) Figure 6: Variation of (a) the spatially integrated fringe pattern and (b) the average fringe shift, with the delay At between the plasma generating laser beam and the 11th harmonic pulses. The delay between harmonic pulses 1 and 2 is x=300fs. (b) -600 -400 -200 200 400 600 Delay At (fs) In the second experiment, we performed frequency-domain interferometry, using two phase-locked harmonic pulses delayed in time, to measure with a 200 fs time resolution the dynamics of ionization in a high density helium jet under intense laser pulse irradiation (UHI10 laser, 100 mJ, 50 fs) - see Section II-2-c. Calling At the delay between the mid-point of harmonic probe pulses 1 and 2 and the ionizing pulse (so that harmonic pulse 1 (2) propagates through the medium at delay At-x/2 (At+x/2) from the ionizing pulse; At+x/2<0 when probe pulses are before pump), we measured the evolution of the spectral interference pattern as a function of the delay, i.e. of the time-dependent relative phase-shift between the two probe pulses. This evolution is illustrated in Figure 6: a phase-shift (a and b) develops from the zero reference when both probes propagate before pump, to a maximum when the pump ionizes the medium in between the probe pulses (At=0), then decreases when both probe pulses propagate after the pump. The time-dependent electron density is easily derived from the phase-shift. The two feasibility experiments show that it should be possible in the near future to probe densities as high as 10"J electrons/cm with a temporal resolution of a few 10 fs. 38 II-2-e Measurements of ultra-fast electron relaxation on a-SiO2 using harmonics H. Merdji, B. Carre, J.F. Hergott, L. Le Dtroff, P. Salieres Collaboration: F. Quere, S. Guizard, P. Martin, G. Petite Ultra-short XUV light pulses synchronized with a laser have the potential for many applications of the pump-i-probe type in solid state and surface physics, since ultra-short characteristic times are in general involved in these dense ordered phases. Time-resolved studies of the relaxation of excited electrons in the conduction band (CB) in a dielectric material provide good examples of possible applications. In the pump+probe experiment that we have performed in a-SiOi, we use the 25th harmonic (39 eV, 50 fs) of LUCA laser to excite electrons of the valence band (VB) into the CB, with kinetic energy up to 30 eV above the Fermi level [Que're' 2000, Martin 2000] - the excitation scheme is illustrated in Figure 7. From the t~0 time of excitation, the electrons can release their energy either by collisional ionization or phonon exchange with the lattice. We measure the energy distribution of electrons in the CB by ultra-violet photoelectron spectroscopy (UPS). ( 1! Ik Figure 7: H25 pump+ IR probe scheme for studying the relaxation of excited electrons in the CB of a dielectric material. u'-c k 1-125 . I) 0 t Calling f(s, t) the energy distribution of electrons in the CB at time t (e is the kinetic energy), we assume that, as a first approximation, the UPS spectrum with the pump alone can be interpreted as fhe/(£, t*=0) distribution immediately after excitation, i.e. the valence band excitation profile. Note that this applies first to the high energy edge of the distribution: the UPS spectrum at lower energy already includes the electrons which have released their energy. The f(e, t=0) distribution is sketched as a solid blue line in Figure 7. Then, we probe the f(e,t) distribution at later time t (sketched as a dashed green line in Figure 7), using 800nm (1.55 eV) or 400 nm, 50 fs laser pulses to further excite the electrons in the CB. After efficient excitation by the probe pulse, the energy distribution is shifted by one IR photon energy and the form of the UPS spectrum is therefore f(e+hViR,i) (dotted red line in Figure 7). As the delay t increases, the spectrum shifts back to the spectrum corresponding to H25 alone. Two-color UPS spectra have been measured at different delays, which display (he above features. In Figure 8, we monitor directly the relaxation process by measuring the photoelectron signal f{e-fh Vm, t)-/(£, t^O) as a function of time but for three energies e fixed in the high edge spectrum. At negative delays (t<0), the fast rising front between 150 and 200 fs corresponds to the inter-correlation of the pump and probe pulses. The two-color signal reaches a maximum at zero delay and then decreases. Using a kinetic model, we estimate i) an energy-loss rate through e-phonon collision of 70 meV/ps at e ~30eV, much lower than would be expected theoretically, and ii) a rate for collisional ionization of 1/40 ps'1, an equally low value with respect to usual optical breakdown models. Our results should be confirmed in further experiments already planned. They show that more elaborate models are needed to describe the electron dynamics at high kinetic energy in the conduction band. 39 6- E=30.8 eV Figure 8: Measured electron signal as a function of pump-probe delay for three energies in the high 4 - -••Vy energy part of the spectrum: solid line. Simulations: dotted line 30 - E = 32 eV 1 5 - J X E=36 eV 04- 02- 0 20 40 60 80 Delay (ps) II-2-f Conclusions - Perspectives The work achieved in the period 1998-2000 has proven that the topic of high harmonic generation retains its potential for new fundamental developments and original applications. Characterization, phase matching studies and optimization: From a basic understanding of the process, we have shown that the parameters relevant to HHG can be actually controlled and adjusted to obtain an optimum of the conversion efficiency, the spatial coherence or the beam quality. Forthcoming optimization studies will again consider various geometries of the generating medium, e.g. large cross-section medium to make full use of the available laser energy. Characterization and control of the harmonic far field wave front using the Shack-Hartmann technique is already planned. Generation of subfemtosecond pulses: Several techniques for obtaining femto or subfemtosecond XUV pulses have been proposed. The first is a direct result of using the ultra-short (<5 fs) laser pulses that are now produced. A second technique relies on the fact that the harmonic pulse is frequency-chirped (through the time- dependent factors such as Oq in the harmonic phase) and can therefore be recompressed to a ~lfs duration. To introduce the third technique, it should be recalled that N harmonics which are resolved in the spectral domain are coherently emitted in the medium as bursts of light at each half-period T/2 of the laser field, these bursts of T/2N duration (-1016 s for N=10) forming a periodical train. Now, various means based on the control of the laser polarization can serve to extract one of the ultra-short, broad-band pulse from the train. The future program on HHG includes generation, transport and characterization of attosecond pulses in the context of the TMR ATTO network. Applications of ultra-short coherent XUV: Applications are a major part of HHG work, which obviously depend on optimization. On the one hand, the relatively high intensities obtained support the search for non linear processes in the XUV. On the other hand, time-resolved studies of the pump+probe type implying coherent XUV certainly make the best possible use of harmonics. Time-resolved measurement of the electron density in an over-critical plasma on solid target has already been attempted. Studies on reflective surfaces submitted to ultra-short perturbations are also planned. 40 П-2-g Selected references Bouhal A., Salières P., Breger P., Agostini P., Hamoniaux G., Mysyrowicz A., Antonetti A., Muller H. G., Phys. Rev. A. 58, 389 (1998). Colombeau В., Dohnalik T., Froehly C, Acta Phys. Pol. A 78, 85 (1990). Constant E., Garzella D., Mével E., Dorrer C, Leblanc С, Salin F., Agostini P., Phys. Rev. Lett. 82,1668 (1999). Descamps D., Lyngâ C, Norm J., L'Huillier A., Wahlström C.-G., Hergott J.-F., Merdji H., Salières P., Bellini M., and Hänsch T. W., Optics Lett. 25, 135 (2000). Gontier Y., Phys. Rev. A 59 4747 (1999). Lange H. R., Chiron A., Ripoche J.-F., Mysyrowicz A., Brega P., Agostini P., Phys. Rev. Lett. 81, 1611 (1998). Le DéroffL., Salières P., Carré В., Optics Lett. 23, 1544 (1998). Le DéroffL., Salières P., Carré В., Joyeux D., Phalippou D., Monot P., D'Oliveira P., Auguste T., Merdji H., Hergott J.-F., Laser Physics 10, 294 (2000a). Le DéroffL., P. Salières, B. Carré, D. Joyeux, D. Phalippou, Phys. Rev. A 61 043802 (2000b). Martin P., Merdji H., Guizard S., Petite G., Quéré F., Carré В., Hergott J.-F., Le Déroff L., Saueres P., Gobert O., Meynadier P., Perdrix M., Laser Physics 10 (1), 270 (2000). Quéré F., Guizard S., Petite G., Martin Ph., Merdji H., Carré В., Hergott J-F, Le Déroff L., Phys. Rev. B 61, 9883 (2000). Salières P., L'Huillier A., Antoine Ph., Lewenstein M., Phys. Rev. Lett., 81, 5544 (1998). Salières P., L'Huillier A., Antoine Ph., Lewenstein M., Adv. Atom. Molec. Opt. Phys. 41, 83 (1999a). Salières P., Le DéroffL., Auguste T., Monot P., D'Oliveira P., Campo D., Hergott J.-F., Merdji H., Carré В., Phys. Rev. Lett. 83, 5483 (1999b). Sheehy В., Martin J. D. D., DiMauro L. F., Agostini P., Shafer K. K., Gaarde M. В., Kulander К. С, Phys. Rev. Lett. 83, 5270 (1999). Spielmann Ch. et al., Science 79, 2967 (1997). Villain P., Lewenstein M., Phys. Rev. A 62, in press (2000). Zerne R. et al, Phys. Rev. Lett., 79, 1006 (1997). 41 П-3 Molecules and clusters in strong fields Permanent research and technical staff: С Cornaggia, M. Schmidt, D. Normand, S. Dobosz, О. Sublemontier, H. Lagadec, T. Blenski, M. Bougeard, E. Caprin PhD students: Ph. Hering, L. Quaglia, M. Segers Post-doctoral positions: M. Lezius, C. Ellert, K. Ishikawa, M. Rusek, L. Le Déroff, T. Ceccotti Undergraduate students: M. Forest (NFIO, Orsay University), M. Bouchon (ESPEO, Orléans) Collaborations: M. Brewczyk (University Bialystok and Center for Theoretical Physics, Warsaw, Poland), E. Charron, A. Suzor-Weiner, (LRC du CEA, Laboratoire de Photophysique Moléculaire, Paris XI, Orsay), J. Viallon, C. Bordas, J. Chevaleyre, M.-A. Lebault (LASIM, Université Lyon I, Villeurbanne), C. Guet, B. A. Huber, (DRFMC/SI2A, CEA Grenoble), M. Faubel (MPI für Strömungsforschung, Göttingen, Germany), M. Wieland, T. Wilhein (Institut für Röntgenphysik, Universität Göttingen, Germany), A.Ya. Faenov, A.I. Magunov, T.A. Pikuz, I.Yu. Skobelev (MISDC of VNIIFTRI, Mendeleevo, Russia). П-3-а Introduction The response of isolated small molecules and clusters to intense laser fields - from 1014 up to 1019 Wem'2 in the femtosecond range - is of fundamental importance in strong field physics. It naturally extends the now widely explored physics of single atoms in strong field, including a number of new many-body or collective processes such as Coulomb explosion, electron impact excitation/ionization. The studies are strongly coupled to other fields in physics and chemistry, from the physics of multi-charged atomic and molecular ions to the plasma physics and XUV source design. In small polyatomic molecules, the studies concentrate on characterizing as completely as possible the dynamics of the multi-ionization - either sequential or direct - and subsequent Coulomb explosion of the multi-charged system. For this purpose, fragmentation channels are thoroughly identified from charge states, kinetics as well as the internal energy of fragment ions. Correlation techniques and photon detection provide substantial results for molecules like N2, CO2, N2O, which have encouraged new theoretical developments. Clusters have been extensively studied for several years since they bridge the gap between atomic and solid state physics. Surprisingly, strong field studies of clusters started only a few years ago. They gave evidence of spectacular phenomena such as X-ray generation, production of highly-charged ions with high kinetic energies, e.g. Xe30+ ions of 1 MeV [Ditmire 1996], or, recently, fusion events in D2 clusters [Zweiback 1999, Schmidt 1999]. In fact, the small size of the clusters (<10 ran) compared to both the laser wavelength and the typical skin depth of solid targets leads to an efficient coupling between light and matter. Several models of the laser- cluster interaction have been proposed [Thomson 1994, Ditmire 1996, Rose-Petruck 1997]. Most of them emphasize a sequence of phases which can be schematized as i) the OFI (optical field ionization) of the cluster in the rising edge of the laser pulse, ii) the laser-acceleration and re-scattering of the primary electrons, including collisional absorption (inverse bremstrahlung), resonant absorption (for an electron Ne density close to its critical value Nc) and electron-impact ionization, and iii) either Coulomb explosion or hydrodynamic expansion of the cluster plasma. According to recent experiments and calculations in our team, this scenario should be discussed as a function of the pulse duration and cluster size. At present, clusters in strong field yield a new source of intense ultra-short X-ray bursts, which is renewable and debris-free (e.g. rare gas clusters). This is of potential interest for various applications in material processing, medicine and biology. In 1998-2000, we have first extended our strong field studies to metal clusters strongly coupled to the laser field through a giant dipole resonance, as well as to laser-produced plasma in liquid jet target. Secondly, we have made the first observation of opacity effects in a molecular cluster jet plasma. The experimental work on both the molecules and clusters in strong laser field has supported the development of new theoretical models in the context of either quantum chemistry, Thomas-Fermi models or classical Monte-Carlo methods. 42 H-3-b Molecular multi-ionization and Coulomb explosion Ph. Hering, L. Quaglia, M. Forest, C. Cornaggia Collaboration: M. Brewczyk, E. Charron, A. Suzor-Weiner Molecular multi-ionization is investigated following three research lines. The first one is aimed at studying non-sequential electron emission processes. Secondly, the overall fragmentation dynamics of Coulomb explosion is probed with a high resolution. The two sets of results are the basis for new theoretical developments by our collaborators in Orsay and Warsaw. Finally, experiments have been performed to detect the fluorescence of excited multi-charged atomic fragments and to correlate the spectra obtained to the electronic excited states of the multi-charged molecular precursors. Non-sequential double and multiple ionization Non-sequential double ionization (NSDI) of a wide variety of molecules (N2, CO2, C2H2...) has been extensively studied in a linearly polarized laser field by ion yield measurements. All the double ionization channels, i.e. the metastable molecular dication and the two-missing electron fragmentation channels, are detected in the experiment. In order to discuss the either sequential or direct type of double ionization, the results are compared in Figure 9 with the predictions of a sequential model in the 1O13-1O15 W/cm2 laser intensity range. For single ionization, a good agreement is obtained with a tunneling model extended to molecules [Cornaggia 2000]. According to the e-2e re-scattering model [Corkum 1993], NSDI is caused by the first ejected electron returning to the core, provided its kinetic energy exceeds the ionization potential of the singly-charged molecule. At laser intensities where NSDI appears experimentally, the energy gained in the laser field by the returning electron is much too low and cannot explain a classical re-scattering process. However, the experimental results do not rule out the possibility of exciting singly-charged molecules by the returning electron. Actually, the Orsay itheoretical group has worked out a deeper insight from the exact resolution of the Schrodinger equation with 2 active electrons in a one-dimensional N2 model molecule. The main features of the experimental curves are now reproduced [Pegarkov 1999]. : | : .: i 101 - Seq""mode ^55 • I101 / J r : Figure 9: Ion yields vs. peak laser intensity recorded 9 for N2 at a reference pressure of Iff Torr. jp / -r—i " NC • io ••• ,/ 10"7 10l 10 10 10" Peak laser intensity (W/cm2) Coulomb explosion: theory versus experiments The experimental studies of Coulomb explosion of small molecules in strong field raise challenging problems for non-perturbative theories of molecules in strong fields. In the experiments, the multi-fragmentation channels are identified from accurate measurements of kinetic energy releases, taking advantage of the high repetition rate (kHz) of the 800 nm, 40 fs SOFOCKLE laser of DRECAM, and making extensive use of powerful ion-ion and ion-ion-ion correlation techniques [Hering 1999]. Different detection procedures show that toe kinetic energy releases are independent of the respective directions of the laser electric field and internuclear axis for linear systems such as N2, CO2, or N2O, although the systems are aligned along the laser field direction. Until now, most of the models have been developed for a one-dimensional model diatomic molecule, while 2D- or 3D-models are required for polyatomic systems. M. Brewczyk has proposed a 43 hydrodynamic model that we have successfully tested in a 2D description of diatomic molecules like N2 and triatomic molecules like CO2 (Figure 10) or N2O [Hering 2000]. 10J : D Experimental energy : ; • Coulomb energy ; • Hydrodynamic model 1 • Figure 10: Experimental and theoretical kinetic energy releases vs. total number of electrons 2 _l removed in CO2. The non integer value of the I 10 i—i ionization state results from the semi-classical H Thomas-Fermi model. In some cases, a given ionization state corresponds to several fragmentation j + + + 2+ + + • P channels, e.g. CO2**^ O +Cf +O , O +C +O , f ¥ and thus different kinetic energies. 23456789 10 Molecular ionization state Excited transient multi-charged molecules Until now, transient multi-charged molecules have been identified from the fragmentation pattern. However, the internal energy of the molecular ions remains unknown. To go further, fluorescence photon spectroscopy is used to probe excited states of the fragments [Quaglia 2000]. Indeed, the transient excited molecular ions cannot be probed directly because the Coulomb explosion is much faster than the radiative decay. Fluorescence detection is achieved for a wide variety of atomic and molecular species from He to C3H4 in the 15 17 2 1O -1O Wcm" laser intensity range. The photon count rates are higher for molecules such as N2, CO2 or CF4 than for rare gas atoms such as He, Ne or Xe. The occurrence of excited multi-charged species is therefore more probable in molecules than in atoms. The fluorescence spectra are recorded in the 50-150 run wavelength range for different molecules built with identical H, C, N, or O atoms such as NH3, N2, and N2O involving the N atom. The dramatic increase from NH3 to N2O, as shown in Figure 11, indicates that the initial electronic structure plays a determining role in the production of excited multi-charged molecules. Similar results are observed with other molecular species built with the C and O atoms. 4 Nl Figure 11: Photon emission spectra recorded with 2 NH3, N2 and N2O. The atomic N2* (Z = 1, 2, 3) lines are labeled by n° 1-5. The atomic OZ+ {1=1, 2, 0 lli 3) are also indicated by the (*) symbol. £? 20 N. I " « 158 N 100 50 50 60 70 80 90 100 110 120 Wavelength (ntn) Perspectives The interpretation of some of the experimental results depends on a better understanding of the fundamental processes and therefore on a close collaboration with theoreticians. Specifically, the hydrodynamic model will 44 be converted to the non-linear Schrodinger equation. Another attempt based on quantum chemistry, aims at computing the zero-field electronic energies of the multi-charged molecules. Experiments will be performed on a larger range of molecular sizes using both ion and photon detection. In the near future, position-sensitive detection in multi-coincidence techniques will be developed for a simultaneous determination of all the momenta of the ejected fragments. The advent of multi-kHz 20 fs lasers will allow to reduce the probability of ionization, while keeping the required high laser electric fields. In addition, pulse durations of less than 5 fs are now shorter than the vibrational periods, and will enable the investigation of Coulomb explosion of frozen molecules during the laser interaction. Finally, well-established techniques such as cold target recoil-ion momentum spectroscopy will be considered in order to reach very high resolutions in the measurement of molecular relaxation. II-3-c Highly charged ions from rare gas and metal clusters in intense laser fields Ch. Ellert, S. Dobosz, M. Lezius, D. Normand, O. Sublemontier, M. Schmidt Collaborations: J. Viallon, C. Bordas, J. Chevaleyre, C. Guet, B. A. Huber, M.-A. Lebault Metal clusters generally exhibit a more or less pronounced giant dipole resonance in the optical or ultraviolet energy range, which distinguishes them from the van der Waals-bound rare gas clusters. This so-called Mie resonance is associated to the oscillation of the free electron gas in the bulk (plasmon). It should strongly enhance the energy absorption from the laser field, and thus cluster heating and subsequent ionization. In principle, metal clusters enable to study the relative importance of OFI to plasma-induced ionization (plasma- field and electron-impact ionization), and thus to test the various models including these effects. For our first experiments on metal clusters we chose lead because of the high mass, thus increasing the inertial confinement, and high Z, to increase the collisional heating [Ellert 2000a, Viallon 2000]. Figure 12: Pb cluster fragment spectrum measured for a pulse duration of 76 fs (FWHM) and a peak laser intensity of 2.5 1015 Wcm2. 4 6 10 Time of flight (us) Metal clusters of several hundreds of atoms were irradiated with peak intensities of up to 1017 Wcm"2. Highly- charged fragment ions were detected using standard TOF as well as magnetic deflection TOF spectrometer. The Figure 12 shows a typical ion fragment spectrum characterizing the interaction of the lead clusters with the intense laser. A careful analysis shows that charge states up to Pb28+ are produced. A strong dependence of the ionization and heating processes on the laser pulse duration was found. While the resulting ionic fragment spectra are qualitatively similar for rare gas and lead clusters, the kinetic energies for the metal clusters seem however to be significantly lower. n-3-d EUV and fast ion emission from a laser-generated plasma in a liquid jet target Ch. Ellert, D. Normand, M. Schmidt, O. Sublemontier Collaboration: M. Faubel, M. Wieland, T. Wilhein Of particular interest to X-ray microscopy are the X-ray and extreme UV (EUV) emission from laser- produced plasmas in the "water window" 2.4 - 4.4 nm [Thieme 1998], as well as in the 10 - 20 nm range. The latter is especially relevant for the next generation of lithography, enabling structure sizes far below 70 nm [Benschop 1999]. As a renewable dense target of potential interest, we have experimentally considered a liquid jet of either N2 or argon (20(im diameter) exposed to intense laser pulses [Ellert 2000b]. 45 Different issues have been addressed: the dependence of the EUV emission on (1) the laser pulse duration varying from 70 fs to 250 ps and intensities varying respectively from 1016 to 1012 Wcm'2, (2) the target material, (3) the orientation of laser polarization relative to the liquid jet axis. We have analyzed the kinetic energies of the ionic debris. Figure 13 shows a typical EUV spectrum obtained in N2 where the characteristic lines of hydrogen-like N are visible. For nitrogen the EUV intensity at 250 ps was about two orders of magnitude higher than at 70 fs pulse duration. We found a weak dependence of the EUV yield on the laser polarization relative to the liquid jet axis. The kinetic energy of the emitted ions easily exceeded 100 keV for N2 and 200 keV in the case of Ar for a pulse duration of ~2 ps. Moreover, the ionic debris are less energetic with long pulses (>10 ps) than with short pulse durations (<1 ps). 70 fs 1 Figure 13: EUV emission from the liquid nitrogen jet J for different pulse lengths wa-velength [ntn] The above result that EUV emission is optimal with 100 ps or longer pulses when irradiating a liquid jet of low Z atoms (Z=7 for nitrogen), is consistent with previous observations on plasmas from solid targets. Several reasons can be invoked for the less efficient conversion in ultra-short pulses, which involve the contribution of collisional and resonant absorption (i.e. Ne~Nc): i) for very short pulses the small number of optical cycles allows only a few electron-ion collisions, ii) at very high intensity and therefore high electron velocity (» 1014 Wcm"2), the rate of collisional absorption is reduced, iii) the laser pulse duration must be at least as long as the expansion time of the pre-formed plasma, so that electron density decreases to the critical value favoring resonant absorption. To complete the present results, comparative studies of EUV emission from a liquid jet target with and without prepulse could be envisaged. II-3-e X-ray emission from fast expanding molecular cluster plasma S. Dobosz, M. Schmidt, M. Perdrix, P. Meynadier, O. Gobert, C. Ellert, O. Sublemontier, T. Blenski, D. Normand Collaboration: A.Ya. Faenov, A.I. Magunov, T.A. Pikuz, IYu. Skobelev We have studied the X-ray emission from dense argon and CO2 cluster jets irradiated by intense laser pulses of duration 70 fs [Dobosz 1998, Schmidt 1999], Compact, state-of-the-art X-ray spectrographs are used allowing for both spectral and spatial high resolution. Well-resolved He- and H-like oxygen O6+'7+ emission lines in the spectral range 16-18 A are observed in the case of CO2. As shown in Figure 14 we observe substantial line broadening which demonstrates a fast expansion of the cluster plasma, in agreement with previous results on xenon clusters. A detailed analysis of our spectra suggests that fast fragment ions with extremely high start-up energies of up to 1 MeV are produced in large proportion approaching ~10"3. Moreover, the oxygen emission lines present strongly asymmetric profiles, i.e. sharp cut of the red-wing. 46 6+ Figure 14: He-like O lines measured in hot CO2 plasma showing sharp cut of the red-wing, interpreted as a strong opacity effect. We tentatively propose a model that considers strong re-absorption of the line red-wing through photoionization of H- and He-like carbon ions in the hot CO2 plasma as well as of neutral carbon atoms (the red-wing light emitted by ions moving away from the detector propagates across a optically thick medium). To our knowledge, this is the first observation of strong opacity effects in a gas jet target. This interpretation is confirmed by an opacity code modeling radiative transfer in plasmas. II-3-f Theoretical description of small clusters in strong laser fields Two theoretical descriptions of the explosion of rare-gas atomic clusters in strong laser field have been developed in parallel, in particular i) a classical Monte-Carlo model for the molecular dynamics, and ii) a semi-classical, time-dependent Thomas-Fermi model. The two approaches are complementary and differ by their accounts for ionization / recombination processes and electron correlations. Monte Carlo particle dynamics simulations of rare gas cluster explosion in a strong laser field K. Ishikawa, T. Blenski In the Monte Carlo simulation of particle dynamics, the equations of motion of the ions and the free electrons are numerically integrated with the force calculated as the sum of the contributions from the laser field and real Coulomb potentials of the other particles. Free electrons may appear through tunneling and electron impact ionization, and may recombine with ions. This method allows us to follow the motion of both ions and free electrons during the cluster explosion. Concerning the ionization mechanism, our results support the ionization ignition model [Rose-Petruck 1997], in which the combination of the laser, ionic, and electronic fields leads to the production of highly charged ions. The effect of electron impact ionization is negligible. In our results, the dependence of ion kinetic energy on its charge state is approximately quadratic up to a certain value, and linear for higher charge states as shown in Figure 15. This behavior was observed experimentally by Lezius et al. [Lezius 1998] for big clusta-s, who attributed the former to Coulomb explosion and the latter to hydrodynamic expansion. Our simulations show, however, that electrons quit the cluster before they exchange a significant amount of energy with ions, which excludes a hydrodynamic scenario for small clusters. Instead, according to our analysis, this charge-energy relation can be: entirely explained by Coulomb explosion. We find that, while ions are emitted nearly isotropically, the mean ion energy is 10-20 % higher along the laser polarization than perpendicular to it, in agreement with a recent experiment [Springate 2000]. Moreover, electrons are emitted preferably along the laser polarization and their energy extends up to ~ 1.5 keV, in agreement with the experimental features of "warm electrons" [Ditmire 1998]. Although our simulations consider relatively small clusters, the (at least qualitative) agreement with the experiments on large clusters suggests that our conclusions - that the cluster explosion is governed by Coulomb explosion and that electronic contribution to the acceleration of the ions is negligible - might be extrapolated to large clusters as well. 47 Xe 147 7=1.3xlO16W/cm2 7 r=100fe(FWHM) t X= 780 nm Figure 15: Charge dependence of ion energy ofXe14y 5 irradiated by the laser pulse with the given I parameters. c .a 4 •S C q 1 2 1 0 4 6 8 10 12 14 Charge state Q Explosion of small clusters in an intense laser field: Thomas-Fermi model M. Rusek, H. Lagadec, T. Blenski The time-dependent Thomas-Fermi (TDTF) model may be considered as a semi-classical approximation to the quantum dynamics of an electron gas, complementary to the classical Monte-Carlo (MC) model. The MC simulation treats exactly the classical N-body problem of interacting electrons and ions including electron collisions (i.e. classical correlations). However, it uses external formulas to describe electron ionization and recombination. Conversely, in the TDTF model, some quantum effects (a pressure term due to the Pauli principle) are accounted for; both bound and free electrons are described using the same TF electron density so that there is no need for external formulas. However, electron correlations (i. e. electron collisions) are not included explicitly in this mean field formalism. In our TDTF study, the ID-model in [Brewczyk 1998] has been extended to encompass the 3D case explicitly. In addition, we use the correct non-linear kinetic energy functional, valid for a 3D ideal electron gas, and which can take into account some non-zero initial temperature effects. The ground-state structure of a N=55 atomic cluster at T=0 K was obtained by solving simultaneously the Smooth Particle Hydrodynamics equations for the electron fluid and the Newton equations for the nuclei with small viscosity and friction terms. The stationary positions of the pseudo-particles describing the equilibrium electronic density and nuclei positions are illustrated in Figure 16. Then the cluster is exposed to a linearly polarized laser pulse (?L=800 nm, Ax=107 fs ~ 40 optical cycles) with a peak intensity of 1.4xlO15 Wcm"2. It turns out that the explosion is neither instantaneous nor uniform but exhibits a layer- wise dynamics in which the cluster shells are expelled sequentially. Moreover, the explosion is non-isotropic. Nevertheless, there exists a forward-backward symmetry and the laser polarization appears to be a symmetry axis. We find that i) the inner shell starts to expand first, thereby pushing the outer shells, and ii) the ions leaving first are far more energetic than those leaving later. Finally, we have investigated some effects due to a non-zero temperature of the cluster prior to the pulse. Further comparative studies between the MC and TDTF models are in progress. 15 r- 1 10 (• •" *•» * Figure 16: Ground-state structure of a 55-atom cluster. -10 - msam -15 -15 -10 -5 0 10 15 x [a.u.] 48 n-3-g Conclusions - Perspectives Molecules in strong field: the program of a complete and accurate description of the laser-molecule interaction will be continued, including coincidence techniques and use of ultra-short laser pulses on the experimental side, and a close collaboration with theoreticians. Clusters in strong field: trie program at SPAM has investigated various schemes of the laser cluster interaction from rare gas, metal and to molecular clusters as well as liquid jet targets. Emission of X-rays and EUV light but also of highly charged ions was studied. Fusion events from a laser-produced plasma on CD4 molecular clusters have been recently observed and will be further investigated. The theoretical work will be continued since fundamental points of the interaction, e.g. the cluster explosion, are still under discussion. The experimental team has momentarily turned to a more applied but closely-related project (PREUVE) of developing an intense source in the EUV range using cluster jets as the generating medium. II-3-h Selected references Benschop J. P. H., van Dijsseldonk A. J. J., Kaiser W. M, Ockwell D. C, Solid State Techn. 42, 43 (1999). Brewczyk M., Clark C.W., Lewenstein M., Rzazewski K., Phys. Rev. Lett. 80, 1857 (1998). Cornaggia C, Hering Ph., Phys. Rev. A 62, 023403 (2000). CorkumP.B., Phys. Rev. Lett. 71, 1994 (1993). Ditmire T., Donelly T., Rubenchik A.M., Falcone R.W., Perry M.D., Phys. Rev. A 53, 3379 (1996). Ditmire T., Springate E., Tisch J. W. G., Shao Y. L., Mason M. B., Hay N., Marangos J. P., Hutchinson M. H. R., Phys. Rev. A 57, 369 (1998). Dobosz S., Schmidt M., Perdrix M., Meynadier P., Gobert O., Normand D., Faenov A. Ya., Magunov A.I., Pikuz T.A., Skobelev I.Yu., Andreev N.E., J.E.T.P Lett. 68,485 (1998). Ellert Ch., Dobosz S., Lezius M., Normand D., Sublemontier O., Schmidt M., Viallon J., Bordas C, Chevaleyre J., Guet C, Huber A., Lebault M.-A., submitted to Phys Rev. A (2000a). Ellert C, Normand D., Schmidt M., Sublemontier O., Faubel M., Wieland M., Wilhein T., submitted to Phys. Rev. E (2000b). Hering Ph., Cornaggia C, Phys. Rev. A 59, 2836 (1999). Hering Ph., Brewczyk, M., Cornaggia C, sumitted to Phys. Rev. Lett. (2000). Lezius, M., Dobosz S., Normand D., Schmidt M., Phys. Rev. Lett. 80, 261 (1998). Pegarkov A., Charron E., Suzor-Weiner A., J. Phys . B: At. Mol. Opt. Phys. 32, L363 (1999). Quaglia L., Cornaggia C, Phys. Rev. Lett. 84, 4565 (2000). Rose-PetruckC, Shafer K. J., Wilson K. R., Barty C. P. J., Phys. Rev. A55,1182 (1997). Schmidt M., Perdrix M., Meynadier P., Gobert O., Normand D., Ellert Ch., Blenski T., Faenov A. Ya., Magunov A.I., Pikuz T.A., Skobelev I.Yu., Andreev N.E., J.E.T.P 88, 1122 (1999). Springate E., Hay N., Tisch J. W. G., Mason M. B., Ditmire T., Hutchinson M. H. R., Marangos J. P., Phys. Rev. A 61, 063201 (2000). Thieme J., Schmahl G., Rudolph D., Umbach E., X-Ray Microscopy and Spectromicroscopy, Springer Verlag, Berlin (1998). Thomson B.D., McPherson A., Boyer K., Rhodes C.K., J. Phys . B: At. Mol. Opt. Phys. 27, 4391 (1994). Viallon J. , PhD thesis, Universit6 Claude Bernard Lyonl (June 22, 2000). Zweiback J., Smith R.A., Cowan T.E., Hays G., Wharton K.B., Yanovsky V.P., Ditmire T., Phys. Rev. Lett. 84, 2634 (2000) 49 II-4 Ultra-short non LTE plasmas produced by Optical Field Ionization Permanent research and technical staff: T. Auguste, P. Monot, P.D'Oliveira, S. Dobosz, M. Bougeard, E. Caprin PhD student: S. Hulin Collaborations: A. Faenov, T. Pikuz, I.Yu. Skobelev (Multicharged Ions Spectra Data Center of VNIIFTRI, Mendeleevo, Moscow, Russia), S. Jacquemot, L. Bonnet, E. Lefebvre (DPTA, CEA/DAM en He de France), A.G. Zhidkov, A. Sasaki, T. Tajima (Advance Photon Research Center, JAERI Osaka, Japan), F.B. Rosmej (TU-Darmstadt. Institut fur Kernphysik, Germany). II-4-a Introduction Plasma physics was first developed at SPAM some ten years ago, as the necessary extension of atom-laser interaction studies to the macroscopic scale. Today, high power ultra-short lasers such as UHI10 make it possible to study highly charged and dense non-LTE plasmas produced either in a gaseous or on a solid target, where a number of processes take place. Particularly interesting is the initially cold dense plasma produced in a gas target from optical field ionization (OFI). On the one hand, the electron dynamics in the OFI plasma is first tightly driven by the laser field, leading to specific processes of channeling or charged particle acceleration. In turn, these dynamics are involved in determining the propagation of the laser field, as in the spectacular regime of relativistic self-focusing. On the other hand, the possibility of an X-ray laser has been demonstrated in the OFI plasma [Nagata 1993], In collaboration with the Departement de Physique Thebrique et Applique^ (DPTA) of the CEA/DAM, the UHI10 team has been investigating for two years the conditions suitable for coherent X-ray emission in a H-like nitrogen plasma produced by OFI. Although not yet confirmed, the scheme still under development promises to produce ultra-short coherent X-ray from a limited energy input (<1 J), through a very efficient coupling of this energy to the medium. The mechanisms for acceleration of electrons and ions over MeV energies are of special interest in non-LTE plasmas. They can find future applications as laser-driven compact sources of energetic particles. In collaboration with the teams of the Multicharged Ions Spectra Data Center (MISDC) in Moscow and the Advance Photon Research Center in Osaka, we have demonstrated ion acceleration over MeV energies by an intense obliquely incident /^-polarized laser pulse focused onto a planar massive target. The physics of transient non-LTE plasmas on UHI10 has multiple links with other topics at SPAM. For example, the transient plasmas produced on dense targets and evolving to over-critical density provide an exemplary system where ultra-short coherent XUV, such as harmonic light, finds full application as a diagnostic tool. II-4-b Towards an X-ray laser using short-duration, high-intensity pulses T. Auguste, P. Monot, P. D'Oliveira, S. Hulin, S. Dobosz Collaboration: A. Faenov, T. Pikuz, S. Jacquemot, L. Bonnet, F. Rosmej We briefly expose the X-ray laser scheme in the case of a nitrogen plasma. We then report measurements of the interaction parameters (density, temperature, laser intensity, interaction length) as well as numerical results, both of which characterize the plasma as a potentially lasing medium. Principle of the femtosecond driven X-ray laser The X-ray laser scheme is based on the fact that OFI, the dominant ionization process in the short pulse/strong field regime, leads to highly charged or fully stripped ions in a dense cold plasma (=10 eV) for a linearly polarized laser pulse. This contrasts with the current schemes, where ionization is ensured by collisional heating in a hot medium. In our study, we have chosen molecular nitrogen as the lasing medium because it is fully stripped at a laser intensity of 1019 Wcm"2, delivering a high electron density (14 eVmolecule). Collisional recombination that preferentially populates high-energy states and radiative recombination that mainly 1/2 populates low energy ones have rates in the ratio ~ NexTe" . Thus for high density and low temperature, a population inversion is induced between the upper and lower states of XUV transitions, giving rise to laser emissioa In particular, two lasing transitions on resonance lines 2p-Ms (25 A) and 3d->2p (134 A) of H-like ions N6* are expected to occur after rapid recombination to N6* excited states, as illustrated in Figure 17. 50 Figure 17:.0FJ-pumped X-ray laser scheme in nitrogen. After fast recombination to H- like nitrogen, lasing transitions are expected between excited states and the fundamental (Lyman a 2p-ls; X~25 A) and OFI between two excited states (Balmer cc 3d- 2p, X~134A). n=2 Lasing transitions Numerical simulations using CHIVAS, LASIX and SUPERSTRUCTURE codes [Eissner 1974, Berthier 1991] were carried out to determine the range of parameters suitable for X-ray lasing. The results show that density as high as 1020 cm"3 is needed together with a temperature in the 10-50 eV range [Hulin 2000]. The interaction length, currently limited to a few tens of um, can be enhanced using relativistic self-focusing, first observed by our team in 1995 [Monot 1995]. Characterization of OFT produced nitrogen plasma as a lasing medium The UHI10 laser used to produce OFI plasma is a 800 run, 60 fs, 10 TW peak-power laser based on CPA technique; it is described in the Section I-2-c. Several diagnostic tools can be installed in the interaction chamber, such as shadowgraphy, Thomson and X-ray imaging, visible to XUV interferometry, visible to X- ray spectroscopy, electron spectrometry. We illustrate how the important parameters in the plasma are consistently determined. Neutral and electronic density A special gas puffing device has been developed which delivers high neutral densities [Auguste 1999]. Using a 2D Mach-Zehnder interferometer, we measured a maximum neutral density of 1.5xlO19 cm"3, over a 2 cm-long medium, and a 2xlO20 cm""1 electron density over a few hundred micron length. Figure 18: 2D-map of the electron density in a nitrogen plasma, in units oflO20 cm'3. The maximum density is 2.102 cm'3. The laser propagates from the E right to the left of the figure. S ;.f :.-» :.2 :.o c.s o.s ».4 0.2 X [mm] .„ Figure 18 shows a 2D-map of the electron density, plotted in units of 10 cm'3, and measured with a 50 fs time resolution. The maximum electron density is 2xlO20 cm"3, and fully stripped ions are produced. The ratio of the laser power to the critical power for relativistic self-focusing is up to 50. Hence, conditions for both self-focusing and coherent X-ray emission are fulfilled. Note that measuring higher electron densities becomes difficult with conventional interferometry in the visible range. Interferometry using ultra-short XUV harmonic light has been developed for extending time-resolved diagnostics to near-critical until over-critical densities - see Section II-2-d. 51 Temperature and peak intensity Plasma temperature is probed by X-ray spectrometry using the FSSR-2D Bragg diffraction-based spectrometer [Pikuz 1995]. Figure 19 shows nitrogen emission in the spectral window from 18.9 to 19.6 A. 25C — theory: nirii'-ls n"{" 200- Figure 19: Emission spectrum of nitrogen in the 18.9-19.6 A range. The lines show that N7+ is generated. The MARIA code calculations reproduce the experimental data for a 30 eV electronic temperature. 1.90 1.92 1.94 1.96 X (nm) The spectrum reveals an accumulation of dielectronic He-like satellite lines from doubly excited N5+, the latter 7+ s+ + produced by double charge exchange N +N2--» N +2N . According to tunnel ionization rate, ionization to N/+ shows that the laser intensity exceeds 1019 Wcm"2 in the plasma. The simulations of the spectra with the MARIA-code [Rosmej 1997, 1999] give an electron temperature of 30 eV for which recombination emission occurs. Interaction length An image of the Thomson emission at 90° from the propagation direction is shown in Figure 20, which emphasizes the periodic structure in the emission, characteristic of self-focusing. 0.2 Figure 20: Image of the scattered light at the laser 0-1 wavelength (Thomson emission). The self-focused ao beam propagates over 18 times the natural -0.1 propagation length ZR. -0.2 2.0 1.0 0.5 0.0 X(mm) The self-focused beam propagates over 1.2 mm which corresponds to 18 times the Rayleigh length. Using a pinhole camera (100 um spatial resolution) with appropriate filters, we detect H-like resonance lines from the same region, confirming the diagnostics from Figure 18 that the laser intensity exceeds 1019 Wcm"2 in the plasma. Complementary time-resolved ombroscopic snapshots indicate that the non-linear propagation is limited by absorption (mainly due to parametric heating) and plasma-induced refraction of the laser beam. n-4-c Acceleration of charged particles in dense plasmas T. Auguste, P. Monot, P. D'Oliveira, S. Hulin, S. Dobosz Collaboration: A. Faenov, T. Pikuz, l.Yu. Skobelev, A.G. Zhidkov, A. Sasaki, T. Tajima At high laser intensities I>1018 Wcm"2, a large part of the energy absorbed by the dense plasmas produced on solid targets is coupled to the emission of energetic ions. First, energetic supra-thermal electrons are produced by OFI on the rising edge of the pulse. Then these electrons induce a strong electrostatic field at the plasma surface that drives the fast plasma expansion. It has been predicted that OFI and plasma-induced field ionization can be more efficient than collisional ionization in the low-density plasma corona, leading to highly- charged states and subsequent energetic ion emission. In order to understand the mechanism for producing energetic ions and its role in plasma energy balance, we have measured the X-ray emission from multicharged ions produced by focusing the UHI10 laser at intensities (2-4)xlO18 Wcm"2 onto a teflon target [Zhidkov 1999]. To correlate the emission of fast ions to hot electrons, the energy distribution of suprathermal electrons was also measured, using electron spectrometry. 52 Energetic ions Time-integrated spectra of the Is2p-ls2 line of He-like fluorine ions measured in a direction (a) perpendicular and (b) parallel to the target surface are shown in Figure 21. The obliquely incident laser wave was p- polarized. The spectrum (a) recorded along the plasma expansion clearly exhibits a blue wing corresponding to MeV ions in the plasma corona. The ion velocity distribution is close to a self-similar one, N(v) « Noxexp(- v/Cs), where Cs is the ion sound speed determined by supra-thermal electrons of -100 keV. In spectrum (b) recorded along the target surface, the analysis of the line red-wing emitted in the target plan leads to a temperature of 1.5 to 2 keV of the plasma bulk. The same asymmetry was observed on the profile of the Is3p- ls2 line of He-like, and 2p-ls line of H-like ions. 1 20 - (a) / - III A 1 15 1 / 60 - Ex. u O i- 10 5 - e J 5 20 i 0 16.4 16.8 17.2 16.4 16.8 17.2 Wavelength (A) Wavelength (A) Figure 21: Spectra of the Is2p-ls2 line of He-like fluorine recorded in a direction (a) perpendicular, and (b) parallel to the teflon target. The obliquely incident laser beam was ^-polarized and the focused intensity was 4XI018 W/cm2. Supra-thermal elections Hot electron distributions in the 0.6-2.2 MeV, obtained with a magnetic spectrometer, are shown in Figure 22 for two laser intensities. One can see that the energy cut-off around 2 MeV weakly depends on the laser intensity in the (l-4)xlO18 Wcm"2 range. The electron energy distribution calculated with a collisional electromagnetic Particle-in-Cell (PIC) code for 4xlO18 Wcm"2 (dotted line in Figure 22) shows a good agreement with the measured ones in the 0.8-1.5 MeV energy range. The model emphasizes that the distribution includes transient populations of hot electrons with different temperatures. The mechanism generating supra-thermal electrons was found to be vacuum heating [Gibbon 1992], constrained by the ponderomotive force. Figure 22: Hot electron distribution. Comparison of the PIC calculation with the measured distribution in the MeV region. Experimental: (1) /= l.3xltf\ (2) 4x10"* Wcm2; calculated for 1= 4xl&8 Wcm2: dotted line. 0.4 0.8 1.2 1.6 Energy (MeV) II-4-d Conclusions - Perspectives In the X-ray laser studies, the different diagnostics show that, in the OFI nitrogen plasma we produce with 60 fs, 10l9 Wcm'2 laser pulses, fully stripped ions and a low temperature (30 eV) can be obtained over lengths much larger than the Rayleigh range. We show that relativistic self-channeling can enhance the laser intensity, i.e. OFI efficiency and interaction length. Under these conditions, the amplification of 2p-ls and 3d-2p 53 transitions is expected during the collisional recombination phase of the plasma. Measurement of an X-ray line is presently under progress giving promising preliminary results. On account of the limited energy required in the scheme, X-ray emission with repetition rate in the kHz range now seems achievable. In the experiments on the interaction of an ultra-intense short-pulse laser with solid targets, we have shown that an obliquely incident p-polarized pulse focused at intensity 4xlO18 Wcm"2 can accelerate OFI-produced ions from the plasma corona over MeV energies in the direction of plasma expansion. It was demonstrated that ions are accelerated by the strong electrostatic field generated by supra-thermal electrons. The next experimental step will check the model prediction that the ion energy should increase with the laser intensity and the atomic number of the target material. The studies of MeV ion acceleration in laser-produced plasma are very important for the future development of compact and high repetition rate ion sources. II-4-e Selected references Auguste T., Bougeard M., Caprin E., D'Oliveira P., Monot P., Rev. Sci. Instrum. 70, 2349 (1999). Berthier E., Rapport des activites laser CEEA/CEL-V3.7, 304 (1998); Jacquemot S., Decoster A., Laser Part. Beams 9, 517(1991). Eissner W., Jones M., Nussbaumer N., Comp. Phys. Commun. 8, 270 (1974). Gibbon P., Phys. Rev. Lett. 68, 1535 (1992). Hulin S., Auguste T., D'Oliveira P., Monot P., Jacquemot S., Bonnet L., Lefevre E., Phys. Rev. E 61, 5693 (2000). Nagata Y., Midorikawa K., Kubodera S., Obara M., Tashiro H., Toyoda K., Phys. Rev. Lett. 71, 3774 (1993). Monot P., Auguste T., P. Gibbon P., Jakober F., Mainfray G., Dulieu A., Louis-Jacquet M., Malka G., Miquel J.L., Phys. Rev. Lett. 74, 2953 (1995). Pikuz T.A., Faenov A.Ya, Pikuz S.A., Romanova V.M., Shelkovenko T.A., J. X-Ray Sci. and Tech. 5,323 (1995). Rosmej F.B. et al., J. Phys. B.: At. Mol. Opt. Phys. 30, L819 (1997). Rosmej F.B., Faenov A.Ya., Pikuz T.A., Magunov A.I., Skobelev I.Yu., Auguste T., D'OUveira P., Hulin S., Monot P., Andreev N.E., Chegotov M.V., Veisman M.E., J. Phys. B: At. Mol. and Opt. Phys. 32, L107 (1999). Zhidkov A.G., Sasaki A., Tajima T., Auguste T., D'Oliveira P., Hulin S., Monot P., Faenov A.Ya., Pikuz T.A., Skobelev I.Yu., Phys. Rev. E 60, 3273 (1999). 54 П-5 High energy density matter and atomic physics Permanent research staff: T. Blenski, F. Thais, M. Poirier, J. Pascale PhD students: L. Féret, J.-C. Pain, Collaborations: F. Perrot. P. Arnault, O. Peyrusse, Ch. Reverdin, J.-P. Thébault, Ph. Troussel, F.Mucchielli, С Cherfils, S. Bouquet (CEA/DEF), С Chenais-Popovics, J.-C. Gauthier, M. Fajardo, F. Gilleron (LULI, Ecole Polytechnique), S. Turck-Chièze, J.-P. Chièze, R. Teyssier, A. Benuzzi, (CEA/DAPNIA), L. Poles, Ph. Baclet (CEA/Valduc), K. Eidmann (MPQ-Garching, Germany), С. Bauche-Arnoult, J. Bauche (Lab. Aimé Cotton, Orsay), К. Ishikawa, B.U. Felderhof (RWTH-Aachen, Germany), В. Cichocki (Warsaw University, Poland), Ph. Boduch, M. Chantepie, E. Jacquet, С. Laulhé (CIRIL, LSA, Université de Caen), R.E. Olson (Univ. Missouri-Rolla, USA). П-5-а Introduction The plasma physics and atomic physics theoretical team at SPAM is involved in different research areas, from the interaction of molecules and clusters in strong field to that of high energy density plasmas. The latter is now becoming a dominant topic, while a constant connection with the experimental work at SPAM and collaborating laboratories is maintained. The theoretical activities in the field of the atomic physics of dense plasmas (APDP) started at SPAM at the end of 1997. The long-term motivation is SPAM involvement in the fundamental research on big lasers of future generation (the LDL, the Laser MJ) in the framework of the Groupe d'Investigation sur les Applications Scientifiques des Grands Lasers (GIAS). A shorter-term motivation has been a two-year contract with the CEA Division of the Military Applications (DAM) on the development of the Super-Configuration plasma Opacity code (SCO). APDP is important in plasma spectroscopy, diagnostics and calculation of energy transfer in practically all experiments using dense plasmas (DP). Studies on APDP, and more generally, on electronic properties of DP have a fundamental character, especially in the regimes at high densities where adequate theories do not exist. In some aspects APDP studies can be viewed as an application and extension of the previous atomic spectroscopy studies developed at SPAM. This is especially true for non-equilibrium plasmas where the rates for auto-ionization, dielectronic recombination or electron capture are of first importance. After the end of the experimental studies on atoms with two excited electrons the theoretical expertise in this topic is partly reoriented to find its place in the APDP context. The studies of collisions of multicharged ions (MCI) with atoms or molecules have nevertheless kept their fundamental character and still follow the work of the experimental teams in this field. With the arrival of F. Thais, the activities of our team extended to experiments on DP. They now include, firstly, the participation in the GIAS experiment on Rayleigh-Taylor instabilities, aimed at testing some aspects of modeling supernovae explosions, and secondly, the participation in the opacity measurements performed by the LULI team whose theoretical suppoit is assured by our team. П-5-b Development of the SCO opacity code T. Blenski Collaboration: F. Perrot, Ph. Arnoult, O. Peyrusse The SCO code [Blenski 1997] calculates opacities of DP at local thermodynamic equilibrium (LTE). The code is based on the super-configuration (SC) approximation [Bar-Shalom 1989] that enables absorption spectra to be calculated using only several hundreds of SCs. For each SC one calculates optical transition energies, oscillator strengths and broadening due to terms and configurations, using statistical sums over all configurations in the SC. The use of statistical sums avoids detailed calculations in which the number of configurations would be enormous (millions and more). The contributions of all SCs are added together taking into account their probabilities!. In the reported period we have compared the Average Atom (AAM) and the Super-Configuration (SCM) models. Both the AAM and SCM approaches allow one to calculate thermodynamic averages of relevant observables, as for example the absorption spectra. The AAM method is especially simple since it uses a single one-electron basis for all ions. However, it leads in principle to non-integer shell occupation numbers. The free energy for each ion is quadratic in shell populations. The SCM method enables the one-electron basis for each super-configuration to be optimized and to calculate more accurately the ion free energies. In the 55 SCM, all ions have integer shell occupation numbers, which allows us to deal correctly with exchange effects. In SCM one assumes a linear dependence of the free energy on the shell populations for all configurations from a given SC. This assumption leads to closed formulas for the statistical sums that are calculated by recurrence relations [Bar-Shalom 1989, Blenski 1997]. The AAM and SCM models have been compared in the example of a nickel plasma of 0.1 g/cm3 density at 25 to 150 eV temperatures. They appear complementary although the SCM leads to a much better agreement with experiments allowing us to calculate detailed absorption structures and to take into account important orbital relaxation effects. A new method was proposed and applied to the calculation of the statistical sums [Blenski 2000a]. A new version of the SCO code has been worked out for the CEA Bruyeres-le-CMtel. It allows the term broadening and shift of each transition to be treated either using the SC or the Average Atom wave functions calculated once for all SCs. It can serve to check the errors introduced when using the AA wave-functions, much better adapted for rapid calculations, in the term contributions. We have also studied the role of the one-electron basis (Hartree-Fock versus Density Functional Theory), static screening due to free electrons, and configuration interaction For each super-configuration the code can now use a one-electron basis that is obtained either in the especially developed thermal Hartree-Fock (HFT) approximation [Blenski 1997] or in the Density Functional Theory (DFT) approach. In addition, we have implemented two options for describing the effect of the continuum electron on the atomic structure. In the first, the Average Atom chemical potential is used in the expression of the SC free energy. In the second, the free electron density is calculated in the Thomas-Fermi approximation and the total self-consistent potential of each SC is calculated including the free electron density. In the future, two possible extensions of super-configuration opacity modeb'ng will be considered: a) detailed term account in chosen configurations, b) non-equilibrium regimes. H-5-c Collaboration with the LULI and PHEBUS experimental teams Th. Blenski, F. Thais Collaboration: F. Perrot, P. Renaudin, C. Chenais-Popovics, J.-C. Gauthier, M. Fajardo, F. Gilleron, J.- P. Chieze, S. Turck-Chieze, K. Eidmann, C. Bauche-Arnoult, J. Bauche We have performed preliminary calculations and interpretation of the opacity measurements in iron [Chenais 2000] and nickel, as shown in Figure 23. We have also proposed an experiment on the mixture ZnS, for which some preliminary runs have already been performed. In addition, our code has served in the interpretation of the opacity measurements in germanium and gadolinium plasmas on the Ph6bus laser [Blancard 1999]. A very good agreement between theory and experiment is found in the different cases. The results from the alternative methods, HFT and DFT, in the SCO code, have been compared [Blenski 2000b] and further, compared to the measured absorption spectra due to the 3d-4f transitions in a samarium plasma at temperatures between 8-20 eV and densities ~ 0.005 g/cm3 [Merdji 1998]. We conclude that the two approaches give theoretical spectra in very good agreement with the experimental ones (within 1 eV) so that they cannot be discriminated in the comparison. Similar conclusions were obtained in other cases. The correctness of the DFT one-electron states was important for the extension of the self-consistent super- configuration calculation to the continuum electrons. Similarly, we have compared the above two options relative to the continuum electrons (implemented in the HFT as well as in the DFT frame), also using samarium [Blenski 2000b]. The theoretical spectra from the two options were again very close (within 1 eV in the position of the structures). Transitions involving a loosely bound electron would be more interesting for theory-experiment comparisons but they are weak and more difficult to measure. These studies will be continued in view of possible experiments. Another extension of the SCO code motivated by experiments is the possibility of treating chosen transitions in either the jj-coupling (SOSA, Spin-Orbit-Split-Arrays) or the intermediate coupling (UTA, Unresolved Transition Arrays). It appears that in thejj-coupling, supplemented by the configuration interaction correction, the calculated spectra display too large spin-orbit structures which are not confirmed by experiments, especially in plasmas at low temperatures. This option will be used to improve our treatment of the Configuration Interaction. 56 Figure 23: Measured (—) and calculated transmissions of a nickel plasma (LULI1999). The large structure centered at 13.8 eVcorresponds to the 2p-3d transitions (2p-4d transitions at 12.6 eV). Both theoretical curves are obtained for 24 eV plasma 2 0.4- 3 Theo_24eV_UTA temperature and 0.004 g/cm plasma density. SOS A curve (••••) is calculated in the j-j coupling ; in VTA 0.2 — Theo_24eV_SOSA (—) spin-orbit splitting energy was added to the term 0.0- and configuration broadenings. i • i ^ i ' r 12.8 13.2 13.6 14.0 Photon wavelength [A] II-5-d Linear response theory for atoms in plasma Th. Blenski, J.-C. Pain Collaboration: F. Petrol The linear response theoretical approach became our major objective at the beginning of 1999. We have worked on it in collaboration with F. Perrot (CEA, Bruyeres-le-Chatel). Our approach intends to model the channel mixing involving all, i.e. bound-bound, bound-free and free-free transitions. A new theoretical development has allowed us to separate the first-order free electron wave functions into two parts with only one depending on the perturbing frequency-dependent potential. In principle, it opens the way to correct calculations of the linear response of atoms in plasmas taking into account the dynamics of free electrons on an equal footing with the dynamics of bound electrons [Blenski 2000c]. The corresponding numerical program has been written but does not converge yet, probably due to problems with the dipole terms introduced by free electrons. In future work, first applications will probably be related to calculation of the refractive index of partially ionized plasmas. II-5-e Hydrodynamics experiment on the Phebus laser F. Thais Collaboration: J.-P. Chieze, R. Teyssier, A. Benuzzi, Ch. Reverdin, J.-P. Thebault, Ph. Troussel, F. Mucchielli, C. Cherfils, S. Bouquet, L. Polks, Ph. Baclet The interest for astrophysics of test experiments on large scale lasers has been outlined by the GIAS. In particular, the GIAS supports studies of hydrodynamic instabilities in astrophysical phenomena where they play a key role: supernova explosion, interaction between galaxies. During the explosion of a supernova the radial shock wave propagates into different layers and generates Rayleigh-Taylor (RT) instabilities. We have performed a laser experiment related to the production and the evolution of RT instabilities due to the passage of a shock wave. Such instabilities are suspected to develop at He/H interfaces in the type II supernovae. Astrophysical observations of this type of supernova (e.g. the early appearance in the light curve of y-rays and Compton degraded X-rays from 56Co decay) can be interpreted as the growth of Richtmyer-Meshkov and RT instabilities in the exploding envelope. In our experiment the growth rate of the instabilities is studied for different initial conditions using a bilayer Cu/CH target (CH is for polypropylen) with a sinusoidal (2D) ripple at the interface. Scaling laws seem to indicate that measurements using the Cu/CH target can be used to validate the complex multidimensional simulation [Remington 1999]. The experiment was performed on the PHEBUS laser facility (CEA), in an indirect drive configuration. The first main beam is focused into a gold cavity and converted into thermalized X-ray radiation, which heats the target and creates an ablation shock. The second beam is used to produce a 5 keV backlighter (probe) source. The main measurement is done after a relatively long time (30 ns) and consists of a transverse radiography of the interface with a 10-15 |im resolution. An example of the interface shape at the time of measurement is displayed in Figure 24. A good contrast is obtained using hard X-rays in the radiography. The shock surface is deformed during the hydrodynamic evolution and is no longer planar. The evolution of the shape of the interface could be well reproduced using the hydro-codes developed at DAPNIA [Baclet 2000]. 57 Figure 24: Radiography of the interface Cu-CH at t = 30ns. II-5-f Spectroscopy of two-electron atoms and multi-charged ions M. Poirier, L. Feret, J. Pascale Whereas the above global approach of atomic physics is necessary in dense plasma to deal with the highly- mixed/unresolved level structure of strongly coupled systems, atomic physics of isolated atom, ion, or particle pair in collision, still provides the basis for a detailed computing of observables. Examples are given below and in Section II-5-g. Firstly, as a conclusion to our studies of the large-/ doubly excited states, we have analyzed the influence of polarization effects on the positions [Poirier 1998] and the autoionization widths [Poirier 1999] of alkaline- earth-atom levels using a Coulomb Green's function formalism. The same long-range formalism is also efficient to deal with strong local interactions between series, provided one diagonalizes the Hamiltonian in a subspace spanned by the closely coupled levels. An example in barium is given in Figure 25 where the 6p3/26g (resp. bpwDg) interacts with the 6pm9g (resp. 6pia\4g). We also have calculated [Poirier 2000] level mixing coefficients, positions and widths in helium and multi-charged ions where the Coulomb degeneracy induces a significant configuration mixing. Figure 25: Quantum defects and scaled autoionization widths n3r (atomic units) of the ^Psnng [k=9/2] states of barium, k is the angular momentum in jk coupling. — (resp. —): perturbative second-order computation without (resp. with) quadrupolar interaction at second order; (•): experimental data [Jaffe 1985]; (A) diagonalization procedure including the 6p3n6%-6pm9g or the strong interaction. Secondly, we have studied the spectroscopic properties of the Ar6+ ion from configuration interaction Hartree- Fock calculations using a pseudo-potential [F6ret 1999a]. As previously shown for the Ba atom [F6ret 1998], our theoretical approach is reliable and quite useful for studying doubly-excited states of MCI which are currently formed in double electron capture from atomic or molecular targets. Since accurate data on energy levels of the Ar7+ parent ion are lacking, the determination of the Ar8+ core-valence electron pseudo-potential has made it necessary to study the Ar7+ ion (new estimate of the ground state energy). Our results for Ar7+ and Ar6+ ions have been used to reliably identify photoemission and Auger spectra [F6ret 1999b] observed in single or double electron capture collisions between Ar8+ and atomic or molecular targets. 58 II-5-g Multicharged ion-atom and ion-molecule collisions L. Feret, J. Pascale Collaboration: Ph. Boduch, M. Chantepie, E. Jacquet, C. Laulhe, R.E. Olson. The electron-capture in the collision of multi-charged ions (MCI) with matter is an important process in either non-LTE or LTE laser-produced plasmas, as well as in fusion plasmas in tokamaks. In a fundamental frame, we have studied electron capture between MCI and atoms or molecules in specific connection with the experiments by the group of Caen at GANIL. As a first example of single electron capture, we have studied X8+ + Li(2s)-» X1+(nlm) + Li+ collisions using the Classical Trajectory Monte Carlo (CTMC) method in the 0.1-5 keV/amu projectile energy range. CTMC calculations predict an effect of the projectile core electron, comparing the cases X= O (X8+ bare nucleus) and X= Ar. In the case of Ar, nl states of the captured electron with low /-values are populated at low energies, while the large /-values are preferentially populated at high energies; this has been experimentally observed [Jacquet 1999]. Furthermore, CTMC calculations show that the projectile core electrons also influence the n/m-distributions in the captured electron states, i.e. the degree of polarization of the emission lines. In agreement with the experiment, we find that the degree of polarization takes large positive values at high energies and decreases at low energies. From calculations of electronic energies in the (X7+ + Li)+ molecular system, we have explained the variation with energy of n/m-distributions in terms of dynamical couplings (radial and rotational). On the same lines, we have investigated Kr8+ + Li(2s) collision. Because the energy diagram of Kr7+ ion is very different from that of Ar7+, new features of the electron capture process - such as negative polarization degree at low energies - have been predicted and experimentally observed [Jacquet 1999, 2000]. Finally, we have studied the Ar8+ + Cs(6s and 6p) electron capture collisions. For the first time, we have investigated the influence of alignment in the target excited state, combined with the projectile core electron effect, while only bare or nearly stripped MCI were considered in the previous investigations. The CTMC results and the experimental data obtained at GANEL agree to find a very strong core-electron effect at low energies [Bazin 2000]. However, CTMC calculations show that the 6p alignment influences only weakly the n/-distributions at low energies, as it is also observed experimentally. The work on MCI-atom collisions has proven that the CTMC method is well adapted to predict reliable state- selective electron capture cross-section for various degrees of excitation of the atomic target. This is not only true at high energy but also in the low energy range where the projectile core electron strongly influences the final n/m-distribution of the electron captured. Now, in relation with the experimental program at GANIL, we have started studying the collisions between MCI and molecular targets using the CTMC method, a first step + being the modeling of H2 et H2 targets in their ground vibrational states. This work is presently in progress. n-5-h Conclusion - Perspectives The theoretical work at SPAM and the opacity measurements in collaboration at LULI will be further developed in parallel, in order to work out an efficient simulation tool and test bench for future programs on large-scale laser facilities. Experiments in the context of the GIAS will continue on the same lines. The spectroscopy of multi-electron systems has now merged with the physics of dense plasmas, responding to the demand of an extended theoretical support in this field. At present, the physics of MCI in collision also sustains the interest of the experimentalists, from both a fundamental and an applied point of view, and will be maintained. 59 П-5-i Selected references Baclet Ph. et al, in "Inertial Fusion Sciences and Applications 99", Labaune C, Hogan W. J., Tanaka K. A. Eds., Elsevier, Paris, p. 1083 (2000). Bazin V., Boduch P., Chantepie M., Cremer G., Jacquet E., Kucal H., Lecler D., Pascale J. 2000, submitted to Phys. Rev. A (2000). Bar-Shalom A. et al, Phys. Rev. A 40, 3183 (1989). Blancard C, Braneau J. , Chocs 22, 75 (1999). Blenski Th., Grimaldi A., Perrot F., Phys. Rev. E 55, R4889 (1997). Blenski Th. et al., in "Inertial Fusion Sciences and Applications 99", Labaune C, Hogan W. J., Tanaka K. A. Eds., Elsevier, Paris, p. 1111 (2000a). Blenski Th., Grimaldi A., Perrot F., J. Quant. Spectrosc. Radiât. Transfer 65, 91 (2000b). Blenski Th., "Photoabsorption in dense plasmas", Astrophys. J. Suppl. Ser., 127, 275 (2000c). Chenais-Popovics C, Merdji H., MissaUa T., Gilleron F., Gauthier J. С, Blenski Th., Perrot F., Klapisch M., Bauche-Arnoult С, Bauche J., Eidmann K., "Opacity Studies on Iron in the 15-30 eV Temperature Range", Astrophys. J. Suppl. Ser., 127, 239 (2000). Chenais-Popovics C, Gilleron F., Fajardo M., Merdji H., Missalla T., Gauthier J. С, Renaudin P., Gary S., Perrot F., Blenski Th., Fölsner W., Eidmann К., J. Quant. Spectrosc. Radiât. Transfer, 65, 117 (2000). Féret L., Pascale J., Phys. Rev. A 55 3585 (1998). Féret L., thesis, Université Paul-Sabatier, Toulouse November 5, (1999a). Féret L., Pascale J., J. Phys. В 32 4175 (1999b). Ishikawa K., Felderhof B. U., Blenski Th., Cichocki В., J. Plasma Phys. 60, 787 (1998). Jacquet E., Chantepie M., Boduch Ph., Lauhlé C, Lecler D., Pascale J., J. Phys. В 32 1151 (1999). Jacquet E., Kucal H., Bazin V., Boduch P., Chantepie M., Cremer G., Lauhlé C, Lecler D., Pascale J., submitted to Phys. Rev. A (2000). Jaffe S. M., Kachru R., van Linden van den Heuvell H. В., Gallagher T. F., Phys. Rev. A 32,1480 (1985). Merdji H., Missalla T., Blenski T., Perrot F., Gauthier J.C., Eidmann К., Chenais-Popovics С, Phys. Rev. E 57, 1042 (1998). Poirier M., Semaoune R., J. Phys. В 31,1443 (1998). Poirier M., Semaoune R., Phys. Rev. A 59, 3471 (1999). Poirier M., submitted to Phys. Rev. A (2000). Remington В. A. et al, Science, 284,1488 (1999). 60 Ill PHYSICAL CHEMISTRY OF MOLECULAR SYSTEMS III-l General presentation 63 III-2 Photophysics and Photochemistry in the Gaseous Phase. 64 III-2-a Introduction 64 III-2-b Structure and energetics of hydrogen bonded complexes: application to molecules 64 of biological interest III-2-c Solvation of metal ions 65 III-2-d Photoinduced charge transfer in molecular clusters: case of anthracene 66 III-2-e Real time dynamics in molecular clusters: the solvation of inorganic salts 66 III-2-f Organic gas phase femtochemistry 67 III-2-g Cluster isolated chemical reactions 67 IH-2-h Conclusions and perspectives 68 III-2-i Selected references 69 III-3 Photo-physical chemistry in the condensed phase 71 III-3-a Introduction 71 III-3-b Solvation dynamics versus geometrical relaxation of molecules in solution 71 III-3-c Columnar liquid crystals: model systems for a quantitative description of energy 72 transport processes III-3-d Benzene and toluene chemical sensors 73 III-3-e Conclusions and perspectives 73 III-3-f Selected references 74 III-4 Nanometric Covalent Systems 75 III-4-a Introduction 75 III-4-b Ceramic nanopowders 76 III-4-c Nanocarbons by Laser Pyrolysis 77 Fullerenes Synthetic Aromatic Carbon as cosmic dust model III-4-d Nano-crystalline component of cosmic dust 78 Infrared emission of diamond grains in circumstellar envelopes. Size effects in the photoluminescence of silicon nano-crystallites and Extended Red Emission III-4-e Conclusions and perspectives 80 III-4-f Selected references 81 61 III-5 Physical Chemistry with Synchrotron Radiation III-5-a Introduction 82 III-5-b Towards transient absorption spectroscopy of biomimetic systems: a two color 82 FEL + synchrotron radiation experiment IIl-5-c Rotational cooling after photoionization probed by Laser Induced Huorescence 83 III-5-d Dissociation of core excited molecules after resonant excitation 84 III-5-e Break down of the Two-step Model in Molecular Normal Auger Decay 85 III-5-f Future trends 86 III-5-g Selected references 87 •6 Theoretical chemistry 88 III-6-a Introduction 88 III-6-b Intermolecular potential 88 Charge distribution Repulsion-dispersion potential (vapor-liquid equilibria calculation) Calculation and modeling charge transfer Ion-molecule Clusters III-6-c Molecular dynamics 91 Results of standard potential Matrix isolation of naphthalene molecule III-6-d Prospects 92 III-6-e Selected references 92 62 III. PHYSICAL CHEMISTRY OF MOLECULAR SYSTEMS in. 1. General presentation The reorganization of SPAM in 1999 was a good opportunity to bring together, in a common administrative structure, those researchers, both experimentalists and theoreticians, involved in physical chemistry, by creating the group "Physical Chemistry of Molecular Systems". At the same time, the team "Photophysical chemistry in condeased phases", consisting of CNRS researchers initially located at the Service de Chimie Moleeulaire, joined the group. Within this context, we made a proposal for the creation of the "Laboratoire Francis Perrin" (LFP) which will allow us to transform the CEA group into a CEA, CNRS and University Paris XI joint laboratory. The objective of this laboratory will be the study of interaction of molecular systems with light (IR, visible, VUV or XUV) at moderate intensities. A whole range of systems will be; examined: isolated molecules, clusters, solutions, liquid crystals, and nanomaterials. Although many collaborations already exist among various laboratory teams (especially with the theoretical chemistry team), the preparation of the LFP proposal gave the occasion of numerous discussions and pxarnitted the emergence of new synergies. Thus, each project featuring in the LFP proposal involves members of different teams in the group. The scientific projects of the LFP have been classified into five main topics: • Reaction dynamics. Elementary processes are investigated at various degrees of complexity and time scales down to picosecond or femtosecond resolution. • Nanometric clusters: size effects and reactivity. Large clusters are studied either as models for interstellar dusts or as chemical nanoreactors for heterogeneous chemistry. • Photo-physical chemistry of biomimetic systems. Photoinduced processes (energy and charge transfer, ionization...) occurring in DNA and proteins are investigated on the molecular level, using model systems. Tliis is a new project created within the LFP framework. • Nanomaterials: synthesis, reactivity and applications. This part groups subjects that are related to potential applications in materials (ceramics, carbon nanomaterials) or pollution control (chemical sensors). • Development of theoretical tools. Besides their close connections with the experimentalists, the theoreticians develop malels aiming at the description of the examined properties on the molecular level. For this presentation of the group activity during the last two years before the creation of LFP, we have kept to the structure corresponding to the five teams making up the group "Photophysics and Photochemistry in Gas Phase", "Photo-Physical chemistry in condensed phases", "Nanometric Covalent Systems", "Synchrotron Radiation Team", and "Theoretical Chemistry". The projects in each part are only summarized, a complete description is available in the LFP proposal. 63 Ш-2 Photophysics and Photochemistry in the Gaseous Phase. Permanent research and technical staff: I. Dimicoli, P.R. Fournier, M.A. Gaveau, F. Lepetit (from 1999), J.M. Mestdagh, M. Mons, P. Pradel (up to 1999), F. Piuzzi, B. Tardivel, J.P. Visücot, PhD students: M. Briant, G. Grégoire, L. Poisson Post-doctoral position: Q. Zhao Collaborations: С Dedonder-Lardeux, M. Elhanine, С Jouvet, S. Martrenchard, B. Soep, D. Solgadi (Laboratoire de PhotoPhysique Moléculaire, Université Paris XI, Orsay) ; P. Maître (Laboratoire de Chimie Physique, Université Paris Paris XI, Orsay) Ш-2-а Introduction The research conducted by the team Photophysics and Photochemistry in the Gaseous Phase is twofold. The first efforts are oriented towards the characterization of molecular solvation of molecules of biological interest at the microscopic level. Using the approach of small gas-phase complexes, the aim is to get accurate information about the interaction of molecules with their environment, in particular water, the ubiquitous solvent of the living world. Emphasis has been given to the energetics of these systems, owing to the importance of these data for biochemistry modeling. The second exploratory step is to elucidate chemical reaction mechanisms at the molecular level. Hence, the idea is to explore, experimentally, the potential energy surface of the system in order to work out how a reactive system reaches the transition state of the reaction. It is also aimed at determining which force field is responsible for the atomic movements near the transition state, at the moment when chemical bonds are broken and others are formed. The attention is focused, for this purpose, on complex chemical reactions and photochemical processes involving many degrees of freedom, both internal (a large reactive system) and external (a reactive system coupled to a finite size solvent: atomic and molecular clusters). An important aspect of our work is the comparison made between experimental information and theoretical results based on potential-energy surface calculations or dynamics calculations. A great deal of the understanding of the processes listed below originates from fruitful connections between experiment and theory. Work performed during the last two years is centered on the following areas: • Conformational studies of biomimetic molecules and their hydrates by IR spectroscopy • Energetics of hydration of biomimetic molecules • Spectroscopic and collisional properties of metal ions solvated by a finite number of water molecules • Photoinduced charge transfer reactions in molecular clusters • Femtochemistry of solvated inorganic salts • Gas phase organic femtochemistry • Cluster isolated chemical reactions Ш-2-b Structure and energetics of hydrogen bonded complexes: application to molecules of biological interest V. Brenner, I. Dimicoli, P. Millie, M. Mons, F. Piuzzi, B. Tardivel, Q. Zhao Hydrogen bonds play a crucial role in molecular recognition in biological systems. They are responsible for secondary and tertiary protein structures, as well as for their hydration. The possibility of isolating aminoacides or polypeptides in the gas phase forming complexes with water of controlled size, in a supersonic expansion, has permitted UV and IR spectroscopic studies [Mons 1999 a] to be performed, thus giving access to the solvation sites of water as well as to the energetics of the bonding of a water molecule to molecules of biological interest. The latter energetic data are essential for comparison with the modeling of such systems. Following an original experimental idea, the two binding sites of water in the side chain of tryptophan, modeled by an indole molecule have been studied (Figure 1): the major site corresponds to the conventional NH~OH2 hydrogen bond and the secondary site to the so-called я-type hydrogen bond, in which the hydrogen atoms interact with the n aromatic ring of indole [Mons 1999 b]. 64 Figure 1 The structure of these two complexation sites as well as the potential energy surface have been obtained using a semiempirical model coupled with efficient procedures for the exploration of the surface. The H-bonded complex was synthesized in a supersonic expansion and its binding energy (4.84 ± 0.23 kcal/mol) was measured using a two-color laser photofragmentation technique, already successfully applied to the hydration of benzene and phenol [County 1998 a, b]. The non-standard H-bonded complex, not observed with indole, was observed with 1-methyl indole, a substituted indole, in which the formation of the conventional hydrogen bond is hindered. Its binding energy, measured with a similar accuracy (4.10 ± 0.14 kcal/mol), was used as a fair estimate of the binding energy of the 7c-type complex of indole-water, as suggested by our calculations. The small difference in binding energy between the two gas-phase complexes suggests that, although traditionally considered as a highly hydrophobic residue, the side chain of tryptophan is not only able to establish a H-bond with a proton acceptor but can also exhibit significant non-standard interactions with an aqueous environment. Meanwhile, a novel desorption device coupled with a supersonic expansion which allows us to vaporize thermally fragile molecules hats been developed in the laboratory, therefore enabling us to study biomolecules [Piuzzi 2000]. The first results on a DNA base are very promising. A vay well resolved vibronic spectrum of guanine and its complexes with water has been obtained by laser induced fluorescence and mass resolved one- color resonant two-photon ionization indicating the presence of different electronic states and several conformers. III-2-c Solvation of metal ions F. Lepetit, J.M. Mestdagh, L. Poisson, J.P. Visticot Collaboration: P. Maitre Gas phase chemistry of ligated metal ions attracts a lot of interest since it has been realized that ligands attached to the ion, by changing the electronic properties of the ion, also change its chemical properties. This creates the possibility of making ligated ion chemistry more selective than that of bare ions [Dukan-Capron + 1998]. Ligated ions, especially those of general formula M(H20)n , are also attractive because of their role in pollutant chemistry (cleaning of nuclear waste in particular). We shall develop this point in the prospective section ni-2-h. First of all, our work has been to adapt an existing apparatus to experiments in which we can measure reaction cross sections in low energy collisions. We developed a new experimental technique for this purpose, which allows us to have a time-of-flight mass spectrometer in tandem with a reflectron, and the low-energy collision cell in between, without dramatic losses in the energy and mass resolution of the system [Sublemontier 2000]. + + We have focused our attention on the Fe(H2O)n and Co(H2O)n ions, with the originality that n is large enough to go beyond the first solvation shell. Cross sections of collisional fragmentation of these ions by different rare gases have been measured. They indicate that chains of water molecules are attached to the metal ion, even when n is as small as n=3. This was unexpected since theoretical calculations by Bauschlicher et al [Bauschlicher 1991] suggested that up to four water molecules could be directly attached to the metal ion. Theoretical calculations, partly done by P. Maitre from the Laboratoire de Chimie Physique d'Orsay, are in progress to account for these results. 65 m-2-d Photoinduced charge transfer in molecular clusters: case of anthracene V. Brenner, I. Dimicoli, P. Millie, M. Mons, F. Piuzzi, B. Tardivel, Q. Zhao Charge transfer plays an important role in many chemical and biological systems. The molecular systems ideally suited for a detailed study of electron or proton process are van der Waals dimers and higher clusters of aromatic hydrocarbons generated by free jet expansion [Martrenchard-Barra 1998, Martrenchard-Barra 1999]. The observation of excimer emission or/and enhanced ionization efficiency is the signature of electron transfer between the locally excited state and the excimer state of these species. Important additional information can be obtained when configurational isomers are present since structural differences can induce strong changes in dynamics. Excimer emission has been previously reported in the case of benzene, naphthalene, and anthracene and tentatively assigned to the dimer species in absence of selective diagnostics. We have interrogated the anthracene clusters up to n = 6 by a complete set of experimental diagnoses based upon mass-selective resonance enhanced two-photon ionization and laser induced fluorescence as well as theoretical modeling. We were able to provide a complete assignment of the spectral features which rests on several independent sources of information: the electronic spectral shifts and linewidths obtained by ionization and fluorescence, hole-burning spectra, time-decay measurements, time-resolved ionization [Piuzzi 1998, 12 1 Uridat 1998]. All anthracene clusters are characterized by a fast electron transfer (kET > 10 s" ). The effect of clustering (homosolvation effect) has been demonstrated by measuring, for each cluster size, the spectral shifts between the origin transition of the species and that of the bare anthracene molecule. The shifts were found to be additive until n = 3 and to saturate for n = 5 and 6. Surprisingly, the trimer species is very different from the other species since two isomeric forms have been brought to light. One exhibits a structured absorption spectrum with extinction of the excimer emission above a vibrational energy of 400 cm'1 while the other isomeric species exhibits a broad unstructured absorption spectrum and is characterized by the absence of electron transfer or radiative relaxation. The absence of excimer emission for higher vibrational levels for the trimer is very intriguing since it is the first species that presents this kind of behavior, amongst all those investigated in our electron transfer studies in both hetero and homo anthracene clusters [Tramer 1998 a, b]. The nature of the fast non radiative relaxation process which quenches so efficiently the electron transfer for both isomers can be tentatively assigned to an inter system crossing process. The absence of such a process for the other anthracene clusters should be ascribed to differences in the relative positions of the singlet and triplet manifolds. Modeling studies enabled us to derive the configurations of the minima of the potential energy surface for dimer to tetramer species. In particular, in the trimer case one of the minima exhibits a triangular structure in which the three molecules are equivalent. In conclusion, it has been established that electron transfer is a very efficient relaxation process in photoexcited molecular clusters composed of large-size molecules such as anthracene and that this process is strongly structure dependent. DI-2-e Real-time dynamics in molecular clusters: the solvation of inorganic salts V. Brenner, G. Gregoire, I. Dimicoli, P. Millie, M. Mons, F. Piuzzi, Collaborations: C. Dedonder-Lardeux, C. Jouvet, S. Martrenchard, D. Solgadi The dissociation of a salt AB in an ion pair A+ + B' is probably the most simple but also the most spectacular effect been brought to light when studying molecular solvation. We have undertaken the study of charge separation in clusters of Nal with polar molecules, namely water, ammonia and acetonitrile, by several methods, either experimentally (electronic and time-resolved spectroscopy), or theoretically [Gr6goire 1998 a,b]. The electronic structure of the solvated Nal was first investigated on a femtosecond time scale by use of a pump-probe ionization technique [Gr6goire 1998 c]. The charge separation was found to be strongly solvent- selective, reflecting different properties of the Na+1" ion pair according to the nature of the solvent. Charge separation seems to be achieved within a cluster of ten ammonia or seven acetonitrile molecules, whereas no evidence of ion-pair separation was found with water, even for clusters containing more than 50 water molecules. This result has been interpreted in terms of different cluster structures: Nal is embedded in the volume of an ammonia or acetonitrile cluster but sits on the surface of the water cluster, the iodine anion, being poorly solvated, drags the sodium cation outside the cluster. A theoretical study on the binding energies and structures of the ground state Nal (CH3CN)n=i.9 clusters has shown that the potential energy surfaces exhibit two types of structures depending on the size of the cluster [Gregoire 2000a]. For clusters containing up to eight acetonitrile molecules, Nal is sitting on the surface of the 66 cluster with the Na+ and I" ions in contact. For nine acetonitrile molecules, a solvent-separated ion-pair structure becomes energetically more favorable, emphasizing the beginning of the charge-separation reaction, in good agreement with the experimental results. Femtosecond pump-probe ionization experiments on Nal-Sn (S=NH3, H2O) clusters have underlined the different structure of the clusters according to the different solvent molecules [Gr6goire 1998b, 2000b]. Two different physical processes at different time scales have been measured: several hundreds of femtosecond for breaking the Nal bond and several tens of picoseconds for thermalization and evaporation of solvent molecules. In conclusion, the present femtosecond ionization results on solvation dynamics at short times have opened a large original research field [Gr6goire 1998 d]. In particular, temperature effect on solvation can be investigated by controlled heating of the clusters using an IR laser light in a series of salts (Csl for example) or organic molecules with different polar solvents. lH-2-f Organic gas phase femtochemistry J.M. Mestdagh,, J.P. Visticot Collaboration: M. Elhanine, B. Soep We have sought the possibility of an additional activity in real time dynamics. It concerns the prereactive behavior of electronically excited organic molecules [Mestdagh 2000]. As in the previous section, the experiments are conducted using the femtosecond LUCA facility of the DRECAM, and make use of the pump- probe technique. This secondary line of research finds its motivation in the growing interest that organic femtochemistry has attracted over the last ten years. The aim is to unravel the most important steps of a reaction, not only by recording transient populations during a reaction, but also by analyzing the atom movements in the course of a reaction. Our recent studies in this direction concern the photochemistry of alkene molecules. After excitation of the TITZ transition, which is localized on the C=C double bond, the molecules undergo important deformations before decaying to the electronic ground state and dissociating. Our work has shown the complexity of this decay. It involves at least two conical intersections and the passage through an intermediate electronic state. This result seems important since the idea which prevailed on dynamics in an excited state was essentially mono-dimensional and suggested that only the torsion about the C=C bond was important. From our work, it turns out that the real behavior of these molecules is definitely multi-dimensional, a fact that must be taken into account in any further realistic description of these processes. m-2-g Cluster isolated chemical reactions M. Briant, P.R. Foamier, M.A. Gaveau, J.M. Mestdagh, J.P. Visticot The point of this research is the isolation of a single pair of reagents (or a known number of reagents) on a large finite size cluster formed of hundreds or thousands of rare gas atoms. The aim is then to observe the collisional and reactive behavior of the reagents at the surface of the cluster. This field was created in our laboratory and is named CICR, for Cluster /solated Chemical .Reactions. It is now used by M.C. Castex of the Paris-Nord University in collaboration with Prof. Moller (Germany) to study charge transfer reactions [Museur 1999]. Several groups are also active in CICR-like fields, notably those of Scoles in the USA and Toennies in Germany, but their interest is directed towards spectroscopy rather than reaction dynamics [Higgins 1998, Grebenev 2000]. CICR experiments consist in generating a beam of large van der Waals clusters by a supersonic expansion. Collisional pick-up is used to deposit reagents on the clusters, afterwards the reagent carrying clusters are freed from further collisions, either with a foreign gas or other clusters. The only interactions are those between the reagents and the cluster itself. In this sense, a CICR experiment is much simpler than experiments performed in micellar solutions since no migration from one cluster to the other is possible. There is no equivalent to the micelle-micelle migration complications in CICR experiments. We refer to our recent work showing that 2-D chemical thermodynamics and reaction kinetics can be formulated to account for association reactions on clusters [Briant 2000]. Even more interesting is the Ba+N2() reaction, revisited on neon clusters [Gaveau 2000]. As shown in our previous works on argon cluster, the reaction product is either ejected out of the cluster as a hot molecule, or stays solvated within the cluster 67 environment and is rapidly cooled. The interesting new point in neon clusters is that, within the 5JLLS following the reaction, the product BaO still conserves some vibrational excitation and is only weakly bound to the cluster surface. In contrast, within 80 us, it is cooled to ground vibrational level, although still in the electronically metastable a3l level. Very interestingly, however, two different locations are then observed: one with BaO deeply embedded into the cluster surface and one with BaO in the interior of the cluster. This is illustrated in Figure 2, In the 1st jis after reaction 600 700 Wrvelength (nm] Figure 2: scheme of the reaction at the surface of a neon cluster. Just after the reaction, the solvated BaO product is at the surface partly relaxed (chemiluminescent spectrum in the upper part). After 80 /is, the product is vibrationally cold (lower spectrum), partly (narrow hands) or totally (broad bands) embedded in the cluster. ni-2-h Conclusions and perspectives The next prospects of molecular studies are definitely oriented towards biosystems. The development of our original vaporization technique is a primary breakthrough which opens up the possibility towards structural and dynamical studies on true biological molecules and not only biomimetic systems. Secondly, the energetics of the interactions of biomolecules with their environment is one of the most difficult data to obtain, although it is essential for assessment of intermoleeular potentials and biomodeling. • Structural studies of hydrates of biomolecules by IR spectroscopy. This technique combined with ab initio calculations turns out to be a very effective way of characterizing the hydration sites of these molecules. Complexes of guanine with water will be studied by IR-UV hole-burning spectroscopy and the IR spectra will be interpreted with the help of ab initio calculations, performed in collaboration with the team of Theoretical Chemistry. • Energetics of hydrogen bonding in complexes of biomolecules. This technique will be used in the near future to measure the hydration energetics of other molecules of biological interest, in particular that of N-phenyl formamide, which mimics the peptidic bond. This work will be done in Saclay, in collaboration with Prof. Simons' group (Oxford, UK). Using the same methodology, the issue of chiral recognition will also be addressed. It has been recently established that the enantiomeric heterocomplexes of chiral molecules can be distinguished by UV spectroscopy [Le Barbu 1998]. A further step would be to quantify the difference in binding energy for the diastereoisomeric solute-solvent complexes (R-R, S-S vs. R-R, S- R). This will be attempted using our technique on two enantiomeric heterodimers previously studied by UV spectroscopy, in collaboration with the group of F. Lahmani (Laboratoire de Photophysique Moleculaire, Orsay). • Femtosecond dynamics of DNA bases relaxation. The DNA bases are characterized by the quasi absence of radiative relaxation. This could be ascribed to the occurrence of an efficient intersystem crossing process. This also explains the difficulties encountered in ionizing these bases by two-photon resonant enhanced ionization using nanosecond laser pulses. Picosecond or femtosecond pump probe experiments are necessary to get insight into the time domain of the energy transfer. 68 Short-term projects in Cluster Isolated Chemical Reaction concerns reaction processes, which are photoinduced on the cluster. Until now, only spontaneous chemical reactions were observed on the cluster. This does not allow for the degree of control necessary to indicate which aspect of the reaction dynamics is most dramatically affected by the presence of the cluster. We aim to focus our attention on the photoinduced reaction of Ca with HBr in a Ca...HBr complex deposited on large argon clusters. This reaction has been studied largely in free Ca.. .HBr complexes and, by comparison, the effects of the cluster supporting the CICR reaction can be studied. In particular, we expect movements of the H-atom, which are favorable for the reaction in the free Ca...HBr complex, to be blocked by the argon cluster, thus changing the dynamics of the reaction dramatically. Another close idea that we wish to develop is the one relative to collisional properties of solvated metal ions. Approaches in theoretical chemistry are obviously more complicated when the metal ion is heavier. However, there is a lot of interest in this subject. Defining strategies for the treatment of nuclear waste often requires models to describe the solvation of transuranian ions. An important property of these ions, possibly the most important one with regard to their chemistry, is their ability to establish substantial charge transfers with solvent molecules. As a result, the ion-solvent bond is not purely electrostatic. Without working with such heavy ions, it is still possible to contribute to modeling such charge transfer situations. Singly charged cations of metal having a large ionization potential like gold are good candidates. An experimental program has begun in this direction, in close relationship with a theoretical chemistry project of Ph. Millie" and J.P. Dognon. Longer-term projects consist of attempts to develop a universal detection source, adapted to real-time studies of chemical reactions. The example above, relative to organic femtochemistry, has shown the advantages of a real-time experiment to bring in light the evolution of a system from reagents to products on a multidimensional potential energy surface. No existing experiment can yet claim the benefit of an universal detector, which allows to determine which forces are active during a reaction. We aim to explore two directions to develop such a tool: • Photoelectron spectroscopy. Forces are not directly accessible to experiment, however they find their origin into substantial changes in the electron cloud of the reacting system. Therefore, changes in photoelectron spectra app>ear as sensitive probes of the apparition of intramolecular forces. With the hope that such changes are sudden in some cases, it should be possible to monitor the apparition and the time evolution of the forces by just monitoring photoelectron spectra in a femtochemistry experiment. In practice, this should be achieved in an imaging experiment of photoelectron spectra. To further these studies a collaboration has started with D. Parker (U. Nijmegen in Netherland). • Harmonic generation in femtochemistry. The idea is to do pump-probe experiments as in standard femtochemistry experiments, but using the femtosecond VUV harmonic source developed at SPAM to make a one photon ionization of the reaction products. As in the previous project, photoelectron spectroscopy will be the detection tool. A substantial simplification in the interpretation of the photoelectron spectra is expected here as compared to multiphoton ionization. IEE-2-i Selected references Bauschlicher, Jr. C.W., Langhoff S.R., Partridge H., /. Chem. Phys. 94, 2068 (1991). Briant M., Gaveau M.-A, Mestdagh J.-M, Visticot J.-P., J. Chem. Phys. 112,1744 (2000). Courty A, Mons M, Dimicoli I., Piuzzi R, Brenner V., Millie'Ph., J. Phys. Chem. A 102, 4890 (1998a). Courty A., Mons M., Dimicoli I., Piuzzi F., Gaigeot M.P., Brenner V., de Pujo P., Milli6 Ph., J. Phys. Chem. A, 102, 6590 (1998b). Dukan-CapronL., Mestdagh H.( Rolando C, Coord. Chem. Rev. 178-180, 269 (1998). Gaveau M.-A., Briant M., Fournier P.-R., Mestdagh J.-M., Visticot J.-P., Phys. Chem. Chem. Phys. 2, 831 (2000). Grebenev S., Hartmann M., Havenith M., Sartakov B., Toennies J.P., Vilesov A, J. Chem. Phys. 112, 4485 (2000). Gregoire G., Mons M., Dedonder-Lardeux C, Jouvet C, Euro. Phys. J. D. 1, 5 (1998a). 69 Grégoire G., Mons M., Dimicoli L, Dedonder-Lardeux C, Jouvet C, Martrenchard-Barra S., Solgadi D., J. Chern. Phys. 110, 1521 (1998b). Grégoire G., Mons M., Dimicoli L, F. Piuzzi F.,Charron E., Dedonder-Lardeux C, Jouvet C, Martrenchard - Barra S., Solgadi D., Suzor-Weiner A., Euro.Phys. J. D 1, 187 (1998c). Grégoire G., Dimicoli L, Mons M., Dedonder-Lardeux C, Jouvet C, Martrenchard-Barra S., Solgadi D., J. Phys, Chem. A 102, 7896 (1998d). Grégoire G., Brenner V., Millie Ph., J. Phys. Chem A. 104, 5204 (2000a). Grégoire G., Mons M.. Dimicoli I., Dedonder-Lardeux C, Jouvet C, Martrenchard-Barra S., Solgadi D., /. Chem. Phys. 112, 8794 (2000b). Higgins J., Callegari C, Reho J., Stienkemeier F., Ernst W.E., Gutowski M., Scoles G., J. Phys. Chem. A, 102, 4952 (1998). Le Barbu K., Brenner V., Millié Ph., Lahmani F., Zehnacker-Rentien A., J. Phys. Chem. A 102, 128 (1998). Martrenchard-Barra S., Dedonder-Lardeux C, Dimicoli L, Grégoire G., Jouvet С, Solgadi D., Chem. Phys. A 239, 331 (1998). Martrenchard-Barra S., Dedonder-Lardeux C, Jouvet C, Solgadi D., Vervloet M., Grégoire G., Dimicoli I., Chem. Phys.Lett. 310,173 (1999). Mestdagh J.M., Visticot J.P., Elhanine M., Soep В., /. Chem. Phys. 113, 237 (2000). Museur L., Kanaev A.V., Castex M.C., Moussavizadeh L., von Pietrowski R., Möller T., Eur. Phys. J. D 7, 73 (1999). Mons M., Robertson E;G., SnoekL.C, Simons J.P., Chem. Phys. Lett. 310, 423 (1999a). Mons M., Dimicoli I., Piuzzi F., Tardivel В., Brenner,V., Millie P., J. Phys. Chem. A, 103, 9958 (1999b). Piuzzi F., Uridat D., Dimicoli L, Mons M., Tramer A., Le Barbu К., Lahmani F., Zehnacker-Rentien A., Acta Phys. Pol. A95, 121 (1998). Piuzzi F., Dimicoli I., Mons M., Tardivel В., Zhao Q. , Chem. Phys. Lett., 320, 282 (2000). Sublemontier O., Poisson L., Pradel P., Mestdagh J.-M., Visticot J.-P., J. Am. Soc. Mass Spectrom. 11, 160 (2000). Tramer A., Brenner V., Milbe Ph., Piuzzi F., J. Phys. Chem. A, 102, 2798 (1998). Tramer A., Brenner V., Millie Ph., Piuzzi F., J. Phys. Chem. A, 102, 2808 (1998). Uridat D., Brenner V., Dimicoli I., Le Calvé J., Millié Ph., Mons M., Piuzzi F., Chem. Phys. 239,151 (1998). 70 Ш-3 F'hoto-physical chemistry in the condensed phase Permanent research and technical staff: T. Gustavsson, S. Marguet, D. Markovitsi, T.-H. Tran-Thi PhD students: J. Bondkowski, M.-L. Calvo-Muñoz, A. Wlosik Post-doctoral positions, A. Sharonov, M. Schwell Collaborations: P. Argyrakis, L. Gallos (University of Thessaloniki, Greece), A. Ayral, A. El- Mansouri (ENSCM, Montpellier), J.P. Bourgoin. J.C. Mialocq, S. Pommeret (DRECAM/SCM), V. Gulbinas, S. Jursenas (Institut of Physics, Vilnius, Lithuania), S. Kumar (Center for Liquid Crystal Research, Bangalore, India), H. Ringsdorf (University of Mainz, Germany), С Roux (Université de Paris 6), M. Veber (Laboratoire de Physique des Solides, Université Paris XI, Orsay) Ш-3-а Introduction The activities concerning photophysical chemistry in the condensed phase can be differentiated into three main subjects. The first one concerns the investigation of ultrafast relaxation processes of large molecules in solution. To this end, we have in the past few years dedicated a major effort to the development of a highly efficient and versatile fluorescence up-conversion spectrometer (resolution 100 fs). This setup has enabled us to study the role of ultrafast hydrogen bond breaking and making in solvation dynamics [Gustavsson 1998], ultrafast internal conversion in ZnTPP porphyrin by monitoring the S2 fluorescence lifetime (2.35 ps) [Gurzadyan 1998] and nonradiative excited-state relaxation via charge-transfer-induced twisting of N,N- dimethylaminobenzylidene-l,3-indandione(DMABI) [Gulbinas 1999]. A second subject is centered on the photoprocesses in organized molecular systems. On the one hand, we have worked with dimers formed in solutions by triarylpyrylium salts and we have shown that it is possible to characterize the dynamics of the monomer/dimer equilibrium using time-resolved absorption spectroscopy [Lampre 1998]. On the other hand, we have been interested in triphenylene columnar phases which we used as model systems for the study of excitation transport (§111-3-0) and the influence of structural disorder in the photophysical properties [Marguet 1998]. The third subject aims at the elaboration of chemical sensors for air pollutants and relies on our knowledge of the photochemical properties of organic dyes and reactivity in confined media. Ш-3-b Solvation dynamics versus geometrical relaxation of molecules in solution T. Gustavsson, D. Markovitsi Collaborations: V. Gulbinas 550 600 650 Wavelength, nm +: : Figure 3 (a) The studied triarylpyrylium tetrafluoroborates; Ры R = R' = CH3, R" = H, PU12* R = CH3, R' = CnHzs, R" - H, Pn.n: R = R' = C12H2S, R" = H, Pj.12a2.12*' R= CH3, R'=R"= CI2H25(b) Corrected + time-resolved fluorescence spectra ofPj.i2 in hexanol; Xe*=394nm. 71 A subject of wide interest, both from a theoretical and an experimental point of view is to what extent the solvent controls intramolecular relaxation processes such as internal conversion and conformational changes. Multi-dimensional reaction paths have been proposed in the literature but the question of how the solvent and the solute dynamics are coupled with each other remains unanswered. The triarylpyrylium salts shown in Figure 3 are good candidates for studies aiming to elucidate this question. Previously, quantum chemistry calculations predicted the formation of a TICT (twisted intramolecular charge transfer state) state in the gas phase without an energy barrier [Markovitsi 1994], but the nature of this state as well as its dynamics in solution remained badly characterized. We have recently performed an investigation of the excited state relaxation dynamics of four triarylpyrylium cations, differing in the number of dodecyl chains attached to the chromophore [Gulbinas 2000]. Combining these new results with the existing knowledge we are now able to refine the understanding of the fundamental processes responsible for the rapid non-radiative decay. In particular, the dependence on solvent viscosity has been examined and the results are rationalized in terms of excited and ground state relaxation dynamics. The fastest process is the dynamic fluorescence shift, which is related to solvent relaxation. The fluorescence intensity decay is slower and can be attributed to molecular twisting. Interestingly, it seems that these two processes occur more or less independently. The geometrical relaxation reduces fluorescence oscillator strength, but enhances the non-radiative So <— Si internal conversion rate. Molecular back-twisting combined with vibrational relaxation in the ground state is shown to be the last and slowest process of the reaction. HI-3-c Columnar liquid crystals: model systems for a quantitative description of energy transport processes /. Bondkowski, S. Marguet, D. Markovitsi Collaborations: P. Argyrakis, L. Gallos, S. Kumar, H. Ringsdorf Sunlight may be beneficial or harmful to life. While it allows plants to grow, it also causes skin cancer due to overexposure. The molecular processes behind photosynthesis and carcinogenic DNA photo-damage are quite similar. A molecule absorbing light energy becomes excited and can undergo chemical reactions. These reactions are much more efficient if the reacting molecules are "assisted" by many other molecules that collect and transmit energy to their neighbors until it arrives at the site of a chemical reaction—much as rugby players pass the ball along until it crosses the goal line. Using columnar liquid crystals as model systems we obtained a better insight into the molecular level of energy transport properties. Figure 4. Columnar liquid crystals are characterized by a highly anisotropic structure, convenient for the modeling of energy transport. They are usually formed by molecules containing a flat and rigid, disk-like core, surrounded by flexible tails. Their structure corresponds to stacks of disks forming columns. In the present study the stacking distance is 3.6A and the intercolumnar distance 21A First, we tried to understand the mechanism responsible for energy transfer from one molecule to another. The driving force for energy transfer consists of two types of interactions: interactions due to orbital overlap, and electrostatic interactions. With the first type of interaction, molecules exchange energy only if they are very close to or nearly touching one another, while electrostatic interactions are active at relatively greater distances. Until now, only one or the other type of interaction was taken into account in energy transfer studies. We determined the respective strength of each type of interaction and we have shown that they can act simultaneously when energy is transferred in the singlet state [Markovitsi 1999]. In this case, just after light is absorbed, some 100 molecules in the same column exchange energy every lps. The transfer of energy towards neighboring columns will begin only after 1,000 such exchanges have taken place. If the energy is transferred in the triplet state, the exchange time rate is again a few picoseconds but the energy remains in the same column and the migration length is limited by structural defects [Bondkowski 2000]. 72 III-3-d Benzene and toluene chemical sensors M.-L. Calvo-Munoz, T.-H. Tran-Thi, A. Wlosik Collaborations: A. Ayral, J.-P. Bourgoin, A. El-Mansouri, C. Roux Monocyclic Aromatic Hydrocarbons (MAHs) are organic air contaminants emitted into the atmosphere by automobile exhaust or by storage, transfer and handling of fuel. The greatest health risk from exposure to MAHs is due to benzene which is carcinogenic [INRS 1992], though toluene is believed to be neurotoxic [INRS 1991]. Following the framework CE directive of 1996, the new daughter directive on benzene has strengthened the limit value of benzene in the atmosphere to 5 |ig/m3 (1.5 ppb) [OJEC 1999]. Sampling benzene in the urban atmosphere and probing its impact on exposed populations will soon become a priority. The economical impact expected in the future has prompted many laboratories to work on benzene sensors. These sensors make use of opened cavitands [Schierbaum 1994; Dickert 1995] and organic [Leray 1996] or inorganic [Barnard 1991] polymers doped with probe molecules to trap the pollutants. The best performance, 27.5 ppm and a response time of -60 sec is however far from that required. Taking into account the problems encountered by these authors (trapping-detrapping equilibrium, swelling of the polymer host matrix, large variation of the response time), we decided to follow another route. We focus on porous materials based on inorganic and organic/inorganic hybrid polymers, obtained via the sol-gel process. They display the required porosity and rigidity. The pore size of these cage-like materials can be monitored by changing the polymerization parameters and the polarity of the host cavity can be tailored to trap non-polar pollutants. In particular, we used hybrid systems of tetramethoxysilane (TMOS) and rnethyltrimethoxysilane (MeTMOS) to decrease the polarity of the cavities. Figure 5 shows the distribution of the pore radius, determined from adsorption and desorption isotherms, as a function of the ratio of the precursors (TMOS/MeTMOS) and the nature of the material (monolith or thin film). Increasing the MeTMOS component induces two additive effects favorable for benzene and toluene trapping: the pore polarity decreases and the pore radius distribution shifts to higher values [Calvo-Munoz 2000a]. 0 TMOS thin film 1.0 0.02 *:TMOS monolith *-* TMOS/MeTMOS 7/3 s" 0.01 (1 20 40 n> 0.6 •e Jo.4 J^9 TMOS/MeTMOS 4/1 thin film 02 4 6 8 0 500 1000 1500 2000 Pore Radius (A) 0.0 benzene concentration / ppm Figure 5: Pore radius distribution of monolithes Figure 6: Calibration curve for benzene The performance obtained for benzene with a thin film (500 run) of TMOS/MeTMOS 4/1 is 10 ppm (Figure €) and a response time of 60 sec: [Calvo-Munoz 2000b], a record as compared to the literature data. This sensitivity can be further improved by increasing the film thickness and by incorporating fluorescing probes which can interact with the pollutants. ID-3-e Conclusions and perspectives During the past years we developed techniques and methodologies for the study of ultrafast processes of molecules in solution on the one hand, and the investigation of transport properties in organized molecular systems on the other. In the future we intend to use this expertise for the benefit of a new project aimed at understanding, on the molecular level, photoprocesses (electron and proton transfer, excitation transport...) in double-stranded polynucleotides. In order to elucidate the mechanism of the proton transfer, a study of this process involving simpler molecules will be carried out. We will also complete the work, in progress, concerning the spectroscopic characterization of charge transport in columnar phases. With regard to the 73 applied aspects, tailoring the size and polarity of the pores of hybrid organic-inorganic polymers and optimizing the interaction of the pollutant with fluorescing probe molecules will remain our priority with the objective of elaborating cheap, sensitive and selective gas sensors. lH-3-f Selected references Barnard S.M.. Walt D.R. Environ. Sci. Technol. 25,1301(1991). Bondkowski J., PhD thesis, University Paris XI. France, (2000). Calvo-Murioz M.L., Tran-Thi T.H., Roux C, Bougoin J.P., Ayral A., El-Mansouri A., PRA proceedings (2000a) (in press). Calvo-Mufioz M.L., Tran-Thi T.H., Roux C, Air Pollution, (2000b) (in press). Dickert F.L., Reif M, Fresenius J. Anal. Chem., 352, 620 (1995). Gulbinas V., Kodis G., Jursenas S., Valkunas L., Gruodis A., Mialocq J.C., Pommeret S., Gustavsson T., J. Phys. Chem. A 103, 3969 (1999). Gulbinas V., Markovitsi D., Gustavsson T., Karpicz R., Veber M., J. Phys. Chem. A 104, 5181 (2000). Gurzadyan G., Tran-Thi T.-H., Gustavsson T., /. Chem. Phys. 108, 385 (1998). Gustavsson T., Cassara L., Gulbinas V., Gurzadyan G., Mialocq J.C., Pommeret S., Sorgius M., van der Meulen P., J. Phys. Chem. A 102, 4229 (1998). INRS Fiche Toxicologique N°49 (1992). INRS Fiche Toxicologique N°74 (1991). Lai C.S.I., Moody G.J., Thomas J.D.R., Mulligan D.C., Stoddart J.F., Zarzycki R., /. Chem. Soc. Perkin Trans. II, 319(1988). Lampre I., Markovitsi D., Sharonov A., Veber M., Chem. Phys. Lett., 293, 423 (1998). Leray I., PhD thesis, Ecole Normale Superieure de Cachan, France, (1996). Marguet S., Markovitsi D., Millie P., Sigal H., Kumar S., J. Phys. Chem. B. 102, 4697 (1998). Markovitsi D, Sigal H., Ecoffet C, Millie" P., Charra F., Fiorini C, Nunzi J.M., Strzelecka H., Veber M., Jallabert C, Chem. Phys. 182, 69 (1994). Markovitsi D., Marguet S., Gallos L., Sigal H., Millie" P., Argyrakis P., Ringsdorf H., Kumar S., Chem. Phys. Lett. 306, 163 (1999). OJEC (Official Journal of the European Communities)(l999/C 53/07). Schierbaum K.D., Gerlach A., Gopel W., Muller W.M., Vogtle F., Dominik A., Roth, H.J., Fresenius J. Anal. Chem. 349, 372 (1994). 74 Ш-4 Nanometric Covalent Systems Permanent research and technical staff: X. Armand, M. Cauchetier (up to 1999), O. Guillois, N. Herlin- Boime, M. Mayne (from 2000), D. Porterat, С. Reynaud PhD students: A. Galvez, L. Henckes. G. Ledoux, S. Sidis-Petcu Post-doctoral positions: M. Mayne, F. Ténégal Collaborations: D. Bahloul-Hourlier. B. Doucey, P. Goursat (Laboratoire de Science des Procédés Céramiques et Traitements de Surfaces, Université de Limoges), European Network 'Nanomat: Nanopowders preparation and processing', J. Bill, A. Müller (Max Planck Institute, Stuttgart), R. Alexandrescu, I. Voicu (National Institute for Lasers, Plasma and Radiation Physics, Bucarest, Roumania), J. N. Rouzaud, C. Clinard (Centre de Recherche sur la Matière Divisée, Orléans), V. Paillard (Laboratoire de Physique des Solides, Toulouse), F. Huisken (Max Planck Institute für Strömungsforschung, Göttingen, Germany). Ш-4-а Introduction The research theme adopted by our team "Laser powders and Interstellar Dust" is chemical physics of nanosized covalent particles. We are particularly involved in the synthesis and properties of very small silicon and/or carbon based particles, with sizes in the 2-100 ran range. Our objective is to contribute into two research fields apparently very different: material science and astrophysics. In fact, in both cases, similar problems arise, which can be solved by a similar approach. In the material field, silicon and/or carbon based nanoparticles of well-controlled sizes and properties are very attractive for the development of nanostructured materials. In astrophysics, carbon and silicon are the main elements found in cosmic dust, but the determination of the true nature of this dust is still an enigma, particularly for the very small grains component where confinement effects are expected. This determination has to be made through the reproduction of the spectroscopic data available from the astronomers. Thus, the synthesis of silicon and/or carbon-based nanoparticles and the study of their chemical and physical properties (especially optical properties in astrophysics) is the fundamental interest of our laboratory. A major part of our activity is taken up by the development of Infrared CO2 Laser Pyrolysis as a method of nanoparticle synthesis. This prccess is based on the interaction of an IR laser beam with a gas flow containing a molecular species absorbing the IR radiation. The temperature in the interaction zone increases quickly, the reactants decompose, a flame appears and particles nucleate and grow rapidly. This process is versatile because physical and chemical parameters can be easily varied and controlled. The very small particle size and the nearly monodisperse size distribution is essentially due to the short and constant residence time in the reaction zone. The well-defined interaction zone forms a wall-less reactor and allows the formation of very pure powders. By acting on the chemical composition of the precursors mixture, we have been able to form silicon or carbon nanopowders or SiC(N) composite nanopowders doped either with В or with Al and/or Y. An originality of our set-up is that we are able to use both gaseous precursors and liquid precursors thanks to an aerosol introduction device. The properties of the as-formed powders are characterized by different methods in order to correlate their chemical and physical properties to their synthesis conditions. We are particularly interested in their morphological and structural features (shape, agglomeration, size distribution, multistage organization, crystalline order) and in their optical properties (absorption from the UV to the IR, photoluminescence). For the SiCN composite nanopowders, we are interested by their sintering behavior, and then by the thermo- mechanical properties of the sintered nanocomposite materials. Such studies are made in our laboratory but also in collaboration with several laboratories. The main applications concern the Si-based nanopowders such as SiC and SiCN for their interest in ceramic nanomaterials used for thermo-mechanical or electronic or optical applications. The most advanced work corresponding to the elaboration of ceramic nanomaterials and to the improvement of their properties as developed in the first item below. We have also used the capabilities of the Infrared Laser Pyrolysis for the synthesis of nanocarbons (second item) such as fullerenes and nanoparticles of hydrogenated aromatic carbons. In this last case, the motivation corresponds to the astrophysical question of the nature of the cosmic dust. With the same objective, we have paid attention to the role of the nanocrystalline component in this cosmic dust, and showed that nanodiamonds and nanocrystals of silicon can nicely help in the assignment of unidentified astronomical bands (last item). 75 HI-4-b Ceramic nanopowders X. Annand, M. Cauchetier, N. Herlin-Boime, M. Mayne, D. Porterat, F. Tenegal Collaborations: D. Bahloul-Hourlier, B. Doucey, P. Goursat For several years, there has been an increasing interest in nanomaterials, which are materials composed of structural units with a size scale under 100 rim. The aim is to obtain materials with improved properties compared to the properties of conventional materials with a microstructure containing grains on a coarser size scale (generally > 1 u.m). For the specific case of SisNVSiC structural ceramics, a key improvement would be to obtain materials exhibiting a plastic deformation at high temperature. Such a property would allow to manufacture pieces more easily, with a good geometrical precision. In order to obtain this property, it is necessary to develop materials having a microstructure composed of very fine grains with spherical shape. It is then natural to begin the elaboration process with "fine" ceramic powders. In the past years, we have shown that Laser Pyrolysis is an efficient route to such fine nanometric powders. This work has been done in collaboration with the laboratories participating in the Research Group of the CNRS named "Physico- chemistry study of Silicon containing nanophasic ceramic powders" [Mayne 1998, S6n6maud 1998, Flank 1999, T6negal 2000] and inside the European Network "Nanomat". Nanopowders, a few tens of nanometers in size, with a controlled SiCN chemical composition have been synthesized. These powders, mixed with sintering aids (AI2O3 and Y2O3), have been successfully used to elaborate nanomaterials exhibiting promising hot-deformation capabilities {Figure 7). Mixing with sintering aids is always tricky and can generate defects (heterogeneity) degrading the properties of the final material. To eliminate this critical step, the elements of sintering aids (Y, Al, O) have been directly incorporated in the powders during synthesis thanks to the spray set-up for the introduction of reactants in the interaction zone [Cauchetier 1999a]. In these "multi-element" nanopowders, SiCNYAl, the dispersion of Al and Y is homogeneous. First results of the kinetic study of their densification show an improvement attributed to very good dispersion of the sintering elements. This result is very promising [Doucey 1999]. However, the densification of the material is not complete. This limitation is attributed to the low content of Y and Al incorporated in the powder. To overcome this difficulty, different strategies are being developed in our laboratory: the liquid precursors or the aerosol set-up can be changed. Work on the definite control of the chemical composition and the physical properties of these multi-element nanopowders is in progress, in close collaboration with the University of Limoges. 35 Creep behaviour at 13S0°C under 180 MPa 40 50 Figure 7: Creep resistance of a nanocomposite made with SiCN nanopowders compared with that of a monolithic material obtained from commercial Si 3N4 powders. Inserted are photographs of the nanocomposite sample before and after the deformation. 76 Ш-4-с Nanocarbons by Laser Pyrolysis X. Armand, A. Galvez, L. Henckes, M. Cauchetier, N. Herlin-Boime, M. Mayne, D. Porterat, S. SMis- Petcu, C. Reynaud, F. Ténégal Collaboration: R. Alexandrescu, I. Voicu, J.-N. Rouzaud, С Clinard Even if carbon chemistry has been extensively studied, the control of the growth of different forms of carbon is not well mastered. Due to the allotropy of this element, a huge variety of nanoparticles can be formed with very different optical, mechanical or electronic properties. In this extensive family, we have synthesized hollow particles such as fullerenes and hydrogenated aromatic carbon nanoparticles. Fullerenes We have previously shown that laser pyrolysis of a benzene vapor in presence of an oxidant such as N2O leads to the formation of soot with high fullerenes content. In contrast with all other methods, a remarkable property of this process is that the yield of high-weighted ftillerenes (C7o and besides) is most often superior to C6o [Alexandrescu 1998]. Because high-weighted fullerenes are of fundamental and technological interest for encapsulation applications, we have been led to optimize the synthesis process. We have particularly studied the role of the oxidant nature in the reactant mixture, that appears to be critical [Alexandrescu 1998, Cauchetier 1999b, Sidis-Petcu 1999], and evaluated the effect of the СбНб to N2O ratio in the reactant mixture at constant temperature and pressure. From infrared spectra and HPLC (High Performance Liquid Chromatography), it was found that the fullerene content in the soot increases significantly when the C/O ratio decreases and goes to 1 (Figure 8). Even if the C6o yield increases faster than the C70 yield, this later reaches values that make the process promising for high weight fullerene isolation. More investigations are planned to investigate the growth process and to optimize the temperature and pressure parameters at C/O ratio close to 1. Figure 8: Yield of C60 and C70 in carbon soot obtained by laser pyrolysis of CgH6 + N2O as a function of the C/O ratio in the reactant mixture. Synthetic Aromatic Carbon ais cosmic dust model Astronomic observations from UV to IR show the presence of hydrogenated aromatic carbon nanoparticles in cosmic dust. For astrophysicists the unsolved problem of the formation and the structure of these nanoparticles is very important. Many laboratories in the world try to synthesize carbon nanoparticles with spectra similar to astronomical observations, particularly in the infrared range for the interpretation of the so-called Unidentified Infrared Bands. In our laboratory, we have used the infrared laser pyrolysis of small hydrocarbons. The main parameters which govern the synthesis (flame temperature and residence time) have been varied and a family of hydrogenated aromatic carbon nanoparticles has been obtained [Herlin 1998]. Although their infrared spectra demonstrate interesting analogies with observations, the relative intensities of some bands are difficult to reproduce accurately. In particular, between 600 and 1000 cm'1, the bands characteristic of the aromatic C- H out-of-plane bending modes are puzzling. The band at 752 cm"1, corresponding to three or four adjacent H at a ring edge, dominates in our sample spectra, which is never the case in astronomical observations where the band at 885 cm"1, attributed to lone H, is systematically the more intense. However, we observe an interesting tendency when the pyrolysis flame temperature increases: a decrease in the 752 cm"1 / 885 cm"1 intensity ratio suggesting an increase of the mean size of the aromatic units. 77 2.0 - # - 2.0 ' -fi " _ - '> .8 •CJ-i -0.8 C,£ - - 34 C.4 - "-3,* 0.1 - I- 5 2 i.C - 1 1 , , . , . , . 1 0.5 .--..•,:...- c& c.t 0.3 *.o '•* <•* :^ Mean layer extent {L; Figure 9: From the thesis of A. Galvez, skeletonized HRTEM images of laser pyrolysis carbons obtained at 1400°C (on the left) and correlation between the CH out of plane infrared bands intensity and the graphene average fringe size for samples obtained at increasing pyrolysis flame temperature (on the right). To understand the atomic structure responsible for the spectral properties, we have studied the correlation between infrared spectroscopy and multiscale organization given by High Resolution Transmission Electron Microscopy (HRTEM) [Galvez 1999]. By developing a homemade image analysis, original quantitative structural and microtextural data can be extracted from skeletonized HRTEM images. A progressive evolution of the microtexture and the structure is observed as a function of flame temperature. An amorphous like- carbon is obtained below 1000°C. It is made of short, randomly oriented, single graphene layers and L, the average fringe size, is smaller than 0.5 nm. With the flame temperature, L increases slightly, reaching 1.15 nm at 1400°C and a concentric orientation of the layers progressively improves. A turbostratic carbon with a concentric microtexture (Figure 9) is observed at the highest flame temperature. A correlation between infrared properties and organization can be observed. The 752 cm"1 / 885 cm"1 ratio obtained from infrared measurements is found to be a decreasing linear function of the average fringe size (L) given by HRTEM measurements (Figure 9). Thanks to this correlation, the extent of aromatic units can be deduced from an infrared measurement. By comparing the infrared spectra of our nanoparticles with astronomical observations, we can extrapolate that in carbon cosmic dust the size of the aromatic units must be at least 2 nm, i.e. consisting of about 50 cycles. It corresponds to particles bearing several hundred carbon atoms. Experimental efforts to synthesize such particles are being developed. Theoretical work aimed at rationalizing the relation between the infrared band intensities and the size and structure of the aromatic units is also in progress (L. Henckes 2000). ITJ-4-d Nano-crystalline component of cosmic dust O. Guillois, G. Ledoux, D. Porterat, C. Reynaud Collaboration: V. Paillard (Toulouse), F. Huisken (Goettingen) Infrared emission of diamond grains in circumstellar envelopes. Since the discovery of a noticeable amount of small diamond particles in meteorites, the question of their presence in space was opened. We have been able to bring the first evidence of the existence in space of small grains of diamond thanks to the identification of two signatures very specific to these small crystallites [Guillois 1999]. Both signatures appearing in the near infrared emission spectra of Young Stellar Objects, near the well known 3.28 um UIB due to aromatic compounds (Figure 10), had been observed by astronomers for a long time but had so far been unidentified. We have shown that they can undoubtedly be attributed to the stretching vibrations of C-H groups formed by the H-termination of the crystalline faces of diamond. The vibrational properties of such C-H groups are well known from studies devoted to the understanding of the role played by hydrogen atoms in diamond growth. Indeed, thanks to the high resolution infrared spectra available, we have been able to explain the accurate position, the narrow width and the high intensity of the astronomical bands, in total agreement with the known chemical and physical conditions of the circumstellar media where this emission occurs (Figure 10). 78 nombre d'onde (cm1) 3000 2950 2900 2850 1,2.. • C(1H)U! H - Observation astronomique 3.53(im ^ (HD 97048) diamant 0.0 a35 3.40 3.45 3.50 3.55 3.60 Longueur d'onde (jam) Figure 10: Spectroscopic comparison (on the left) between the near-ir emission spectrum observed in circumstellar media and the absorbance spectrum of H-terminated diamond nanocrystals with structure schematized on the right. (Guillois et al, 1999) Size effects in the photoluminescence of silicon nano-crystallites and Extended Red Emission The Extended Red Emission (ERE) is an astrophysical phenomenon that manifests itself in a 120-190 nm broad emission band in the visible spectrum between 600 and 850 nm and has been observed in various regions of interstellar space. It is well accepted that ERE originates in the photoluminescence (PL) of an interstellar dust component. However, the restriction that the quantum efficiency can be larger than 10% has significantly reduced the number of potential candidates. Indeed, carbon particles, such as hydrogenated amorphous carbon and other organic compounds, which have been proposed so far, can now be excluded because of their extremely low PL yields when they emit in the red. Recently, we have shown that crystalline silicon nanoparticles offer several advantageous properties making them attractive candidates for ERE [Ledoux 1998]. As porous silicon, isolated crystalline Si nanoparticles exhibit bright PL in the red when illuminated by ultraviolet radiation. Moreover, the PL- peak shifts with the size of the nanoparticles due to quantum confinement. Consequently, the whole set of ERE observations could be explained by invoking a single carrier and only assuming different size distributions (i.e. different mean sizes and/or widths). We have carried out a set of designed experiments to corroborate this hypothesis. The silicon nanoparticles were produced by pulsed CO2 laser pyrolysis of silane (SiH4) in a gas flow reactor at the MPI laboratory of Gottingen. A conical nozzle extending into the reaction zone extracts the nanoparticles and transfers them into a molecular beam. Time-of-flight mass spectrometry has shown that the velocity of Si particles in the beam is size-dependent, so that a beam chopper can be used to select different masses with narrow size distribution [Ehbrecht 1999]. Thin films of Si nanoparticles with different mean sizes and size distributions have been produced. High resolution electron microscopy revealed that the Si particles consisted of a nanocrystalline core and a surrounding layer of amorphous SiOx whose thickness is about 10% of the particle size [Hofmeister 1999]. PL studies of as-prepared samples were carried out in our laboratory with a 266 nm laser radiation. The PL yield was determined by accurately measuring the UV power absorbed by the sample and recording the PL photons with a calibrated detection system. As the average particle size is varied from 2.8 nm to 5 nm, the maximum of the PL shifts from 640 nm to 800 nm, and the experimental peak positions agree very well with the theoretical model based on quantum confinement [Ledoux 1999, Ledoux 2000]. When we try to reproduce the observed ERE spectra, it turns out that we can almost always find a laboratory PL curve which is in very close agreement with the astrophysical observations (Figure 11). 79 Figure 11: Comparison between ERE observations (thin lines) in three different nebulae : NGC 2247 (a), NGC 2327 (b) and NGC 2023 (c) and PL of three samples of silicon nanocrystallites (thick lines) of different average sizes : 3.4 nm (a), 3.9 nm (b) and 5 nm (c). The apparent quantum efficiencies range between 8% and 20% for Si nanoparticles with diameters between 3 and 4.5 nm. Atomic force microscopy studies, carried out for submonolayer deposits produced under similar conditions, revealed that the thin films were contaminated by a few larger Si particles (10-30 nm), representing at most 10% of all deposited particles. These larger particles may absorb a substantial part of the exciting radiation, but, regarding the confinement process, they are too large to luminesce efficiently. Taking this effect into account, corrected quantum efficiencies near 100% are determined for Si particles between 3 and 4.5 nm. Moreover, the UV absorption cross section for Si nanocrystals is 10 times larger than for overall interstellar dust. Hence, only a very small proportion of 1% of the dust in the form of Si nanocrystals, either free or embedded in larger grains, enables the observed ERE intensity to be accounted for. 400 500 600 700 800 900 Such sizes small enough to induce quantum effects are known to be Wavelength (nm) present in the lower part of the interstellar dust size distribution, as determined by independent observations. Slight variations in the size distributions of the very small grains allow the observed diffaence in ERE position to be reproduced from one object to another and the progressive shift of ERE with increasing distance from the exciting star. Hence, for the first time, intrinsic size effects in interstellar grains are shown to be the key to the understanding of an astronomical phenomenon. m-4-e Conclusions and perspectives We have shown that Infrared Laser Pyrolysis is a powerful technique to form particles of well controlled chemical composition, size and structure. We are able to contribute to the present development in the field of nanostructured material. Progress in the tailoring of the synthesized particles in connection with the desired properties will be one of our future objectives. For this purpose, we will first develop our spray device for precursor introduction. This is useful for increasing the amount of metallic elements in pre-ceramic nanopowders for our collaboration with the Limoges laboratory. Moreover, we plan to improve this system so as to introduce solutions containing metallic particles able to act as catalyst elements, for example to form nanotubes in a flow reactor. Another objective is to improve the control of the average size of the formed particles, in particular on the smallest size edge, and to limit the agglomeration of the particles, leading to a chain-like structure. In particular, this effort is aimed at investigating the paramagnetic centers and electronic properties of silicon carbide nanomaterials [Charpentier 1999], and their non-linear optical properties. Finally, due to the high interest in the quantum size effects, for astrophysical as well as material science purposes, we have started building a new experimental set-up designed to form a molecular beam of size- controlled nanoparticles from a Infrared Laser Pyrolysis reactor. This set-up, named SONATE for Size- selected Nanoparticles Source, will produce a continuous beam of neutral nanometric clusters. Our objective is to determine the properties of the carbon nanometric clusters as a function of their size and of their structure. We will pay attention to their infrared spectra in order to progress in the field of carbon cosmic dust and its very small grain component. 80 Ill- 4-ff Selected references Alexandrescu R., Armand X., Cauchetier M., Herlin N., Petcu S., Voicu I., Carbon 36, 1285 (1998). Cauchetier M., Armand X., Herlin N., Mayne M., Fusil S.. Lefevre E., J. Materials Science 34, 5257 (1999a). Cauchetier M., Armand X., Herlin N.. Alexandrescu R., Morjan I., Petcu S., Voicu L, Fullerene Science and Technology 7, 91 (1999b). Charpentier S., Kassiba A., Emery J., Cauchetier M., /. Phys. Condens. Matter 11,4887 (1999). Doucey В., Thesis, Limoges University (1999). Ehbrecht M., Huisken F., Phys. Rev. В 59, 2975 (1999) Hank A.-M., Armand X., Cauchetier M., Mayne M., /. Sync. Rad. 6, 512 (1999). Galvez A., Thesis, Orleans University (1999). Guillois O., Ledoux G., Reynaud C, Astrophys. J. Lett. 521, LI33 (1999). Henckes L., Thesis, Université Paris XI, (end november 2000). Herlin N., Bonn I., Reynaud C, Cauchetier M., Galvez A., Rouzaud J.-N., A&A 330, 1127 (1998). Hofmeister H., Huisken F., Kohn В., Em. Phys. J. D 9, 137 (1999) Ledoux G., Ehbrecht M., Guillois O., Huisken F., Köln В., Laguna M.A., Nenner L, Paillard V., Papoular R., Porterai D. Reynaud C, Astron.Astrophys. 333, L39 (1998) Ledoux Gilles, Thesis, Université Lyon I (1999) Ledoux G., Guillois O., Reynaud C, Huisken F., Kohn В., Paillard V., Materials Science & Engineering B69-70, 350 (2000) Mayne M., Bahloul-Hourlier D., Doucey В., Goursat P., Cauchetier M., Herlin N., J. European Ceramic Society 18, 1187 (1998). Sénémaud C, Gheorghiu de la Roque A., Dufour G., Herlin N., J. Appl. Phys., 84, 4945 (1998) Sidis-Petcu Stela, Thesis, Paris XI and Bucarest Universities (1999) Ténégal F., Gheorghiu de La Rocque A., Dufour G., Sénémaud C, Mayne M., Herlin-Boime N., Armand X., Cauchetier M., J. Appl. Phys., 87, 7864 (2000) 81 1H-5 Physical Chemistry with Synchrotron Radiation Permanent research and technical staff: M. E. Couprie, D. Garzella, N. Leclercq, M. Meyer, P. Morin, L. Nahon, M. Simon Ph. D. student: M. Gisselbrecht, A. Marquette, S. Aloise, R. Guillemin, K. Le Guen, D. C6olin Postdoctoral positions: E. Renault, E. Shigemasa, C. Miron Collaborations: A. Gruzmailho (Russia), M. Larzilliere (Laval University, Canada), S. Svensson, O. Bjornholm, S. Sorrensen (Uppsala University, Sweden), A. Naves de Brito (Unicamp, Brazil), D. Lindle, O. Hemmers (Las Vegas University, USA), E. Shigemasa, N. Kosugi (UVSOR, Japan), K. Ueda (Sendei University, Japan) m-5-a Introduction The activity of the Synchrotron Radiation team is focused on the determination of dynamic properties of photoexcited systems from atoms to polyatomic molecules and molecules of biological interest. The SR is a unique tool to excite these systems in the UV-VUV and soft X-Ray photon energy range. Pump-probe experiments as well as sophisticated coincidence experiments have been developed, in which the team has specialized. In the UV range, we are mostly interested in probing photochemical and photophysical processes in the sub-ns and ns time-scales, like internal conversion. SR provides a broad continuum spectrum used to probe (by absorption in the UV) any system initially excited through the FEL laser radiation available on the Super ACO storage ring. Systems of biological interest are under study, in the context of the recently-created LFP laboratory. Most of the team's activity is devoted to the dynamics of core excited molecules (soft X-ray range). Dynamics in this energy range is governed by core hole relaxation (a few fs) and nuclear motion (typically a few 10 to 100 fs), giving rise to interesting competing and interfering processes. Various techniques are used, such as fluorescence and laser-induced fluorescence (i.e. two-color experiments), electron-ion coincidences and angular distribution from fixed-in-space-molecules. The first two techniques are related to energetics and nuclear dynamics, whereas the last one refers to continuum wave function (photoelectron and Auger electron) characterization. As shown later, our studies clearly reveal that excitation and relaxation processes have to be considered as a one-step process. We are also interested in studying dissociation processes of complex molecules to understand the conditions under which selective fragmentation channels can be observed. Numerous collaborations have been established with both experimental and theoretical groups, with exchange programs. m-5-b Towards transient absorption spectroscopy of biomimetic systems: a two-color FEL + synchrotron radiation experiment L. Nahon, M. E. Couprie, D. Garzella, E. Renault A Transient Absorption (TA) spectroscopy experiment on biological samples has been initiated since 1998. It takes advantage of the natural synchronization, pulse-to-pulse, between the Super-ACO UV Free Electron Laser (FEL) and the Synchrotron Radiation (SR) to photoexcite a chromophore in solution with the FEL and probe the relaxation dynamics of the excited state and the associated transient species, by absorption with the white-light continuum provided by a dipolar magnet (beamline SA5 and SB5). The goal is to gather information on the dynamics of photon-induced photochemical and/or photophysical processes on the sub-ns and ns time-scales, on which many non-radiative relaxation processes of the Sn states are occuring. We will be interested in the mechanisms of activity and toxicity of antitumoral drugs such as porphyrins and anthraquinones, studied in solution and during their interaction with DNA. On the long term, possible applications in cancer photochimiotherapy can be foreseen. Besides we plan to investigate the de-excitation of triptophan, the major proteic material absorbing in the UV-B region leading to protein photodegradation, involving an internal proton transfer. More generally, the experiment takes place in the larger framework of photobiology under UV irradiation, with possible applications in the controlled triggering of biochemical reactions acting on the metabolism. 82 As compared to laser-based TA set-ups, the interest of ours is manifold: it is complementary to micro-second and multi nano-second flash lamp/laser photolysis set-ups and to ps and fs laser set-ups, in terms of dynamics. Besides, it is the only way to obtain sub-ns white light pulses in the UV range, since the white light continua generated from ps and fs laser are limited to the visible domain which does not allow the direct probing of many radicals. In addition, laser-generated white light continua, through highly non-linear processes, are very instable, which is not the case of SR-produced continua. During the last two years, our main effort has consisted in demonstrating the feasibility of such an experiment on a model system: the POPOP, an organic molecule used in dye lasers. We clearly observed a two-photon FEL+SR signal, different from the spectrum obtained with the FEL alone (fluorescence) or the SR alone (absorption in the ground state), appearing as an enhanced absorption in the 550-600 nm region. Such a spectral feature is attributed to the absorption from the Ti triplet state produced by Intersystem Crossing (ISC) from the initially FEL-populated Si state. In the first configuration of the experiments, at 8.32 MHz, we could not see any time-dependent signal by tuning the pump-to-probe delay between 0 and 120 ns. This was interpreted as being due to the long-living Ti state which traps all the energy deposited into the system. The spectral modifications induced by the addition of KI, with the iodine heavy atom modifying the ICS rate, confirm this hypothesis. In order to overcome this difficulty, we set up a re-circulation of the solution to refresh the sample in view of the photon beams, and we decreased the repetition rate of the experiment, down to 83.2 kHz, so that the interpulse period (up to 12 jj.s) allowed the decay towards the fundamental ground state. To this end, we used a Pockels cell on the FEL to extract one pulse out of 100, and we gated the detection of the transmitted SR through the spectrometer. As can be seen in Figure 12, the results are very encouraging, since a clear temporal dependence can be observed on the ns time-scale corresponding to transient population of the Si state. This shows the feasibility of the experiments that should be extended to biochemical compounds in the near future. 0.00-, -0.05- Figure 12: Temporal dependence of the two-color < -0.10- < Transient Absorption signal on the POPOP molecule excited at 350 nm and probed at 450 nm, showing the variation of the Sj excited state -0.15- produced by FEL-excitation. -2 0 1 time (ns) 111-5-c Rotational cooling after photoionization probed by Laser Induced Fluorescence M. Meyer, M. Gisselbrecht, A. Marquette, S. Aloise Collaborations: A. Gruzmailho, M. Larzillere In studies dedicated to the investigation of the relaxation processes of molecules, we have analyzed the fluorescence (200 nm < ?l(fluo) < 1000 nm) emitted after innershell excitation of various di- and tri-atomic + 2 molecules [Meyer 1999, Marquette 1999, Marquette 2000a,b]. In particular, the emission of the N2 (A nu) + 2 and N2 (B I^) states [Marquette 1999] has been investigated after resonant excitation of the N2 (IS'-TC*) resonance using monochromatized synchrotron radiation from the new high-resolution beamline SB7 of SuperACO. The vibrational structure of the core excited state as well as of the final ionic state has been resolved in the photoexcitation and in the dispersed fluorescence spectra, respectively. A detailed analysis of the experimental spectra and a comparison with theoretical results show a strong coupling between the + 2 vibrational levels in the core excited and the ionic state produced via autoionization. The N2 (A nu) potential curve is almost parallel to the core excited state which causes mainly (Av = 0) transitions in the autoionization process. For the N2+ (B 2Xu+) state, the production via the n* resonance leads to the population of higher vibrational states which are only very weakly populated by direct ionization. The calculations reproduce the 83 observed structures and underline the complementary character of fluorescence and photoelectron spectroscopy. In the series of investigations using the combination of synchrotron and laser radiation we have been able to perform the first experiments related to dissociation processes of photoexcited molecules. The rotational + distribution of N2 ions produced by autoionization of the ndag and nd5g ^ Rydberg states of N2 has been measured by laser-induced fluorescence (LIF) spectroscopy using a pump probe arrangement. A typical + 2 2 experimental LIF spectrum of the N2 (X Zg, v=0) -» (A nu, v=4) transitions is given together with a + synthesized spectrum in Figure 13. The rotational distribution shows a strong rotational cooling of the N2 ions, i.e. the population of the rotational sublevels is no longer described by a Boltzmann distribution of 300 K, which is expected for an effusive beam. This finding is explained by strong competition between the autoionization process and the pre-dissociation of the Rydberg states into two neutral atomic fragments. A J- dependent dissociation, where high-J levels are related to a high probability of fragmentation, results in + rotational cooling of the N2 ion produced via autoionization. This example illustrates well that the combination of broadband synchrotron excitation and high-resolution laser excitation is an adequate and powerful tool for studying molecular dissociation processes in the VUV region. wavelength (nm) 615 614 613 612 611 610 I I I I . P12 ._—__ P22 >-— P21&Q22 - , rt-^12&Q11 - —• R22&Q21 R11 R21- Figure 13: LIF Spectra recorded on No after SR experimental spectrum photoionization I synthezised spectrum at 50 K ...A- \/\J r •r-- T"»T 16.26 16.28 16.30 16.32 16.34 16.36 16.38 16.40 laser photon energy (cm " x10 ) III-5-d Dissociation of core excited molecules after resonant excitation M. Simon, N. Leclercq, P. Morin, R. GuiUemin, K. Le Guen, D. Ceolin, E. Shigemasa, C, Miron Collaborations: S. Svensson, A. Naves de Brito, K. Veda Core excitation of simple molecules in the soft-X-ray regime offers the possibility of inducing electronic transitions into resonant states with selected vibrational energy. It is thus possible to emphasize the role of nuclear motion in that situation and its interplay with the electronic core-hole relaxation. Of special interest is the 100-1000 eV photon energy range where the core hole life-time is large enough (10 fs and above) to occur on a competitive time scale as compared to nuclear motion. The geometry of the resonant state of course plays a crucial role in the dissociation dynamics of the system. The specificity of our set up is to provide a selection of the ion internal energy through coincidence between energy-analyzed electron and fragment ions. We have studied several molecules (BF3 [Simon 1997], CF4 [Ueda 1999], H2S, CO2 [Morin 2000], N2O [Morin 1998], OCS ...) from which CO2 and CF4 are briefly described here as demonstrative examples of the role of the intermediate state in the dissociation dynamics. According to the core equivalent model, excitation of the Cls-> n* in CO2 gives rise to a bent intermediate state. This lowering of symmetry (Renner-Teller effect) induces a splitting into two configurations AL (bent) and Bj (linear) which can be photoexcited preferentially on the low-energy side (respectively the high-energy side) of the excitation profile. The resonant Auger spectrum is dominated in the valence region by the contribution from the A "TIu state. We have performed e/ion coincidence measurements at 19.1 eV binding energy, corresponding to highly vibrationally excited levels of this A state. Three coincidence spectra are reported below, as recorded on the left, top and right position in the photoexcitation profile. Clearly, O+ + production is favored at low photon energy, whereas at high photon energy unfragmented CO2 is favored. 84 This result shows clearly that the fragmentation pattern is governed not only by the internal energy of the ion but also by the way it has been produced. O+ production is possible at this binding energy only if one takes into account predissociation of the A state through a 4Z repulsive state and a conical intersection induced in the bending coordinate. BE: 19.1 eV CO + o CO* Right II II I ill i VLJ Top 1 HI 111 i ill I I II Li j I il I. i II UUlt 111 Left L±li 800 900 1000 1100 1200 1300 time of flight (ns) Figure 14: coincidence spectra between the A state of COf, recorded along the C7s->/7* resonance profile. The CF4 molecule is another example where core excitation may induce a very specific fragmentation channel. The Cls absorption spectrum of this tetrahedral molecule is dominated by the huge Cls->o* transition into a strongly repulsive state along the C-F coordinate. Recording of resonant Auger spectra along the resonance profile shows a participation of the 2t2 and 3t2 final states in the relaxation. Of special interest are the + coincidence measurements with the 2t2 state which show an exceptional enhancement of the CF2 + F2 + dissociation channel as compared to the CF3 + F competitive dissociation channel. As in the previous example (CO2), we give evidence of a dissociation dynamics effect mediated through resonant excitation. We have also investigated relaxation dynamics from fixed-in-space-molecules, in order to characterize the electron wave function of both photoelectron and Auger electron. HI-5-e Break down of the Two-step Model in Molecular Normal Auger Decay M. Simon, N. Leclercq, P. Morin, R. Guillemin, K. Le Guen, D. Ceolin, C. Miron Collaborations: E. Shigemasa After the fast (a few attoseconds) photoejection of a core electron, it is assumed that the Auger decay takes place in a very short time scale (a few femtoseconds). These two processes are assumed to occur in two well- defined steps. The Post Collision Interaction (PCI) is the limit of this model, and occurs when the kinetic energy of the photoelectron is slow (a few eV). The Auger electrons and the photoelectron exchange some energy. With vibrational resolution, Sundin et al [Sundin 1998] observed this effect for the CO molecule: the B state of CO** is shifted by 30 meV very close to the ionization threshold. We have carried out the first experiment measuring the angular distributions of Auger electrons from fixed-in- space CO molecules by detecting the Auger electrons in coincidence with fragment ions. Two identical ion detectors (cfaanneltrons) with retarding grids were installed at 0° and 90° relative to the polarizaition vector of the incoming light. Because the photodissociation from the Auger final state is considered to occur in a shorter time than the molecular rotation period and along the molecular axis (axial recoil approximation), the two detectors select £ -> X and £ -> Fl transitions, respectively. We used the double toroidal electron analy2:er [Miron 1997], precisely calibrated by well-tabulated angular distributions, for the Auger angular distribution measurements. 85 In Figure 15, we show the angular distribution of the B state with respect to the molecular axis at three different photon energies (299 eV, 305 eV and 400 eV) obtained in coincidence with the two detectors. Within the two-step model, the photoelectron carries the angular momentum away in the first step and the residual ion has the K shell vacancy whose distribution is cylindrical around the molecular axis. 299 eV 305 eV 400 eV 90 90 135 180 channel O 18' 315 225 225 315 270 135 135 n channel 18Ot O ]80j 0 180) 225 270 Figure 15: Angular distribution patterns from fixed in space (II and J. )CO molecule Because the shape and spatial orientations of the electronic orientation of the orbitals of the core ionized molecules are the same for X and FI channels, we should obtain the same angular pattern. Far above threshold (400 eV), as expected, the patterns for Z ad FI channels are almost isotropic. When the energy decreases, we obtain rich structures, markedly different for both channels. On the shape resonance (305 eV), the pattern shows a maximum around 45° and two minima close to 0° and 90° very similar to a 6K wave pattern observed for the Is photoelectrons from fixed-in-space-molecules [Shigemasa 1995]. At 299 eV, the photoelectron has a kinetic energy of only 1 eV and the pattern shows 4 nodal structures. The present observations strongly suggest that the PCI effect induces a dynamical angular correlation between the photoelectron and the Auger electron At present, there are no available theoretical treatments describing our results. m-5-f Future trends The team's research in the near future is strongly linked to the use of third generation synchrotron sources and to the new scientific orientation defined in the LFP laboratory. We will use higher and higher brilliance machines (Max lab in the very near future), taking advantage of both high focusing properties and high spectral resolution. An effort will be made to optimize the various set-ups to benefit from these performances and to make them easier to move. This instrumental effort is necessary to keep our set-up competitive following the orientations already approved in the LURE instrumentation renovation plan ("Ebauche d'un plan de Jouvence des dispositifs experimentaux du LURE", June 1999). Investigation towards biomimetic systems will also be carried out in the context of the LFP laboratory, as an extension of the selective fragmentation studies. 86 Photoionization from fixed-in-space-molecules gives very exciting results that cannot be understood within the framework of a two step picture. We are starting to collaborate with Prof. Cherepkov to develop a new theoretical approach. Finally, the involvement of the team (L.Nahon and M.Meyer) in the TESLA application program is a good opportunity to develop time resolved experiments with a new coherent source. HI-5-g Selected references Gisselbrecht M., thesis, Paris XI University (2000). Marquette A., Meyer M., Sirotti F., Fink R.F., /. Phys. B 32, L325 (1999). Marquette A., Gisselbrecht M., Benten W., Meyer M., Phys. Rev. A 62, 022513 (2000a). Marquette A., thesis, Paris XI University (2000b). Meyer M., Marquette A., Gisselbrecht M., J. Electr. Spectr. 101-103, 81 (1999). Miron C. et al., Rev. Sci. Instrum. 68, 3728 (1997). Morin P., Simon M., Miron C, Leclercq N., Hansen D.L., /. Electr. Spectr. 93, 49 (1998). Morin P., Simon M., Miron C, Leclercq N., Kukk E., Bozek J.D., Berrah N., Phys. Rev. A 61, 701(2000). Shigemasa E. et al., Phys. Rev. Lett. 74, 359 (1995). Simon M., Miron C, Leclerai N., Morin P., Phys. Rev. Lett. 79, 3857 (1997). Sundin S. et al., Phys. Rev. A 58, 2037 (1998). Ueda K., Simon M., Miron C, Leclercq N., Guillemin R., Morin P., Tanaka S., Phys. Rev. Lett. 83, 3800 (1999). 87 ni-6 Theoretical chemistry Permanent research and technical fellow: C. Angelie", V. Brenner, J. P. Dognon, P. Millie", P. de Pujo, J.M. Soudan PhD student: S. Dare-Doyen (codirection with DCC/DPE), J. Delhommelle (codirection with LCP Orsay), A.L. Thomas Postdoctoral positions: G. Granucci, S. Hoyau, F. Rogalewicz-Gilard Collaborations: C. Crepin (Laboratoire de Photophysique Mol6culaire C.N.R.S., Orsay), A. Boutin, A. Fuchs, B. Levy (Laboratoire de Chimie Physique, University Paris XI, Orsay), J.P. Dognon, Ph. Guilbaud, C. Rabbe (DCC/DRRV/SEMP, CEA Marcoule), D. Doizi (DCC/DPE , CEA Saclay) m-6-a Introduction The principal research of the Theoretical Chemistry team is in the area of quantum chemistry and molecular dynamics with a major topic related to structure and dynamics of complex systems. The research field includes development of methods and their application to experimental problems in connection with SPAM teams and CEA, CNRS and university teams. Intermolecular potentials used in our team in the last few years are very suitable for the study of small aggregates [Courty 1998a,b, Le Barbu 1998, Tramer 1998a,b, Mons 1999]. Multipolar multicentric distributions used to calculate electrostatic interactions reproduce with an error of less than \9c dipolar and quadripolar moments derived from ab initio calculations. Moreover, this distribution is weakly conformation-dependent and the use of multipolar expansion improves the representation of electrostatic potential at short distance. If we include dipolar bond polarizability (which is transferable and reproduces the global molecular polarizability with an error lower than 5%) in interaction energy calculation, we have a very accurate tool without the drawbacks of standard charge distributions. But with these accurate intermolecular potentials [Uridat 1998, Coussan 1999], calculation time increases rapidly with system size and major difficulties still remain. Effort had to be made for: • Development of simpler but still realistic mathematical expressions for potentials, • A better accuracy of approximations used in the case of interaction with ions and, particularly, with metallic ions with large polarizing capacity, • Extraction of dispersion forces from ab initio calculation, for neutral systems for which they can never be neglected. We begin to work on the first two points and more precisely, work performed during the last two years is centered on the search for a better representation of molecular interactions (electrostatic interaction, back polarization, charge transfer, etc.), the development of tools for potential energy surface exploration (Monte Carlo growth method [Bertolus 1998, Gr6goire 2000], Car-Parrinello DFT method) and corresponding applications in the area of ion complexation, dimer formation in water, impurity insertion location in a matrix, excitation transfer and excitonic theory [Marguet 1998, Markovitsi 1999, Millie" 1999, Beljonne 2000]. m-6-b Intermolecular potential Charge distribution G. Granucci, J. Delhommelle, V. Brenner, P. Millie Collaborations: B. Levy, S. Durand, C. Rabbe, J.P. Dognon Our goal is to obtain a minimal atomic charge distribution which results in decreasing calculation time, which is able to reproduce ab initio electrostatic potential and is not conformation dependent. This charge distribution could be used for molecular dynamics simulations. To do this, we have used a method already proposed by B. Levy [Levy 1998]. The basic idea is that classical fit of electrostatic potential on a grid could lead to indetermination that could be used to obtain conformational independence and transferability without loss of precision. For example, this method gives good results on a flexible monoamide CH3-CO-N-(C4H9)2 for which a fit with the classical method gives very poor results for nitrogen charge which is hidden [Dognon 2000]. Good results were also obtained on alkanes. For this, we have developed an atomic charge and bond dipole model that is only weakly dependent on conformation and converges to a limit when increasing the length of alkane chain. So we can obtain, without calculation, charge distribution on any non-branched long alkane [Delhommelle 1999]. Repulsion-dispersion potential (vapor-liquid equilibria calculation) /. Delhommelle, P. Millie Collaborations: A. Fuchs, A. Boutin Predictive numerical simulation of binary mixtures or pure component could be used in industrial processes. The usual method for these simulations is first to choose an analytical form for the intermolecular potential for each component. Then, with calculation and experimental characterization, one adjusts parameters of the potential. In a mixture, Lorentz-Berthelot combination rules are used to obtain dispersion-repulsion parameters from pure components. This method is not very suitable if we want general potentials because, if terms are missing in the potential formulation, the fit gives parameters with no physical meaning and no reasons to obey combination rules. As a result, we do not obtain transferable potentials. So how may we predict quantitatively thermodynamic properties? We have shown in thiols R-S-H and sulfurs R-S-R' (R, R'=alkyl) compounds that describing electrostatic interaction very precisely for one element in the series is sufficient to obtain Lennard- Jones parameters able to predict vapor-liquid thermodynamic diagram quite satisfactorily [Delhommelle 2000]. Calculation and modeling charge transfer S. Hoyau, A.L. Thomas, V. Brenner, P. Millie, J. M. Soudan Collaboration: J.P. Dognon The study of properties of complexes between organic ligands and ions in liquid phase is usually carried out using molecular dynamics. For example, such simulations are performed in nuclear fuel reprocessing research in CEA/Marcoule (liquid-liquid extraction). Standard model potentials are not very accurate to describe molecule-ion interaction, generally because they do not include polarization and/or charge transfer. Work on polarization is in progress with the aim of taking into account the back polarization term. We present here only the work carried out to model charge transfer in order to allow for it in molecular dynamics simulations. A second step involves studying simple ion-molecule systems and clusters. > Ion-molecule The main goal of the present work was first to evidence the charge transfer contribution, then to quantify it, partitioning the interaction energy in its main contributions (electrostatic, polarization, repulsion and charge transfer), and finally to model it with an analytical term as simple and as accurate as possible. We have proposed a new method of partitioning interaction energy (in HF, MP2 or DFT framework) and of calculating the charge transfer term. We have also determined the orbitals involved in the charge transfer. 2+ 2+ 2+ 2+ 2+ 2+ The [H:!O-Cat ] systems with Cat =Ca , Zn , Cd , Hg were studied in a first step as well known simple 3+ model systems. Thereafter the same procedure was applied to small lanthanide [H2O-Ln ] systems. Calculations have been carried out for ions with several effective core potentials. For +2 charged cations, the charge transfer occurs from a lone pair of the water oxygen to a virtual ns orbital for the cation (Figure 16). 2+ 2+ As expected, H2O-Ca does not exhibit charge transfer and H2O-Hg exhibits the largest charge transfer. 2+ 2+ 2+ Intermediate contributions were obtained for Zn and Cd . For H2O-Hg , the variation of the charge transfer term has been studied as a function of angles of approach of the cation and a simple relationship has been found between the charge transfer and overlap integrals (between orbitals involved in the charge transfer). For +3 charged lanthanide cations, charge transfer is not negligible contrary to classic ideas. In lanthanum compounds it represents 20% of the interaction energy. In this case, only CI calculation in a non-orthogonal basis set allows the analysis of charge transfer (n and a contributions). For lanthanum or lutetium compounds, the charge transfer involves essentially 5d unoccupied orbitals (Figure 16). 89 HO-Hg" (CT— 6s Hg) 3+ H2O-La 5dLa) ,v 0.015 e : 0.068 e 0.023 e Figure 16 Clusters + If we now consider the {metal-(molecule)n} system, the charge transfer can be described (in a valence bond framework) by the interaction between different mesomeric forms: • metar-(molecule)n, + • metal-molecule -(molecule)n-i, + • metal-molecule-molecule -(molecule) n.2 • etc. Therefore, we have to calculate non-diagonal and diagonal corresponding matrix elements. We begin our work with the molecule-molecule system (Figure 17). One can easily show that in the general framework of Hartree-Fock theory, the non-diagonal matrix element is equal to the Fock matrix element (obtained from Hartree-Fock orbitals of neutral system) between localized orbitals involved in the charge transfer. A state H \ f/ NH3-NH3 NH3-NH3 H H H Figure 17 In order to test these approximations, we performed calculations taking into account correlation effects and polarization of orbitals. For example, in Q geometry (Figure 17), we calculate the energy of both Au and Ag states. At long distance (>5 A), the energy difference between these two states is effectively found to be twice the Fock matrix element (difference < 3%). Consequently, the correlation and polarization were negligible. For smaller distances (2.5A or less), a difference lower than 25% is found. Then, we try to correlate the value of the Fock matrix element and the overlap between the two orbitals involved in charge transfer. We found a linear relationship. This work is not complete yet and we will work in the future on other geometries and on metal-molecule systems, exactly in the same way, using selected CI. 90 ni-6-c Molecular dynamics Results of standard potential S. Dare-Doyen, P. Millie Collaboration: D. Doizi, P. Guilbaud In order to test potentials included in standard molecular dynamics simulation software (AMBER), we have studied a process that is difficult to model because the results are dependent on compensations of forces from several origins. Molecules like pyronines or rhodamines (used as laser dyes), that are positively charged, form dimers in aqueous solution. Experimental evidence of this association exists and we can obtain structural information for dimer from NMR measurements. Our simulations are essentially carried out putting two dye molecules and associated counter-ions in a water box with periodic boundary conditions. We study both the evolution of the formed dimer during the molecular dynamics simulation and the formation (or not!) of the dimer from its two separated components. In both these cases, the dimer is stable and the average structure is in good agreement with NMR information. This shows that potential deficiency could be hidden in complex systems. This formation of a dimer in aqueous solution for plane and rigid molecules could be compared to the change in conformation observed for flexible molecules in aqueous solution that hides their hydrophobic part. Matrix isolation of naphthalene molecule P. de Pujo, V. Brenner, P. Millie Collaboration: C. Crepin Recent experimental fluorescence spectra obtained by C. Crepin and colleagues with naphthalene trapped in an argon matrix suggest the existence of two main kinds of sites in the matrix. In order to confirm this hypothesis, we have developed an original method of matrix formation simulation by molecular dynamics. We simulated the condensation of a gas on a cooled argon medium on a molecular scale by collision of gas particles with a surface made up of some argon solid layers. For an efficient simulation time, it is necessary to adjust collision frequency, gas particle mean path and temperature. Scaling factors were applied according to experimental conditions. Contrary to other methods, no degrees of freedom were freezed. In this manner all possible particle displacements are allowed, leading to a full relaxation. The calculations show the presence of two types of site, a first one with 4 argon atoms substituted in the plane of the naphthalene molecule, a second one with 5 argon atoms substituted (Figure 18). A slight deformation of the matrix near the naphthalene molecule is observed. Modification of neighborhood (and of course difference of volume between the micro-cavities taking the impurity) has led to a proposed qualitative interpretation of experimental shifts and evolution in bandwidth. 0 © © © © O Figure 18 91 IQ-6-d Prospects In the near future, we will carry out work to develop general potentials and to extend areas of applications. We plan to carry out work in the field of: Intermolecular potentials Repulsion-dispersion and hydrogen bond (V. Brenner), Metallic ion-molecule systems (and especially heavy elements like lanthanides) (A.L. Thomas, J.P. Dognon), Case of electronic excited states (P. Millie"). Molecular dynamics Monte-Carlo/Molecular dynamics simulations comparisons (F. Rogalewicz-Gilard), Relaxation dynamics (comparison cluster-liquid phase) (J.M. Soudan), Combined statistical-dynamical approach (C. Angeli6), Vibrational spectroscopy of covalent structures (P. de Pujo, J.P. Dognon). DI-6-e Selected references Beljonne D., Cornel 1, Silbey R., Millie" Ph., Br6das J.L., /. Chem. Phys. 112, 4749 (2000). Bertolus M., Brenner V., Millie" Ph., Eur. Phys. J. D 1, 197 (1998). Courty A., Mons M., Dimicoli I., Piuzzi F., Brenner V., Millie" Ph., /. Phys. Chem. A 102, 4890 (1998a). Courty A., Mons M., Dimicoli I., Piuzzi F., Gaigeot M.P., Brenner V., de Pujo P., Millie" Ph., /. Phys. Chem. A 102, 6590 (1998b). Coussan S., Bouteiller Y., Perchard J.P., Brenner V., Millie Ph., Zheng W.Q., Talbot F., /. Chem. Phys. 110, 10046 (1999). Delhommelle J., Granucci G., Brenner V., Millie Ph., Boutin A., Fuchs A.H., Mol. Phys. 97, 117 (1999). Delhommelle J., Tschirwitz C, Ungerer P., Granucci G., Millie" Ph., Pattou D., Fuchs A.H., J. Phys. Chem. B 104, 4745 (2000). Dognon J.P., Durand S., Granucci G., Levy B., Millie Ph., Rabbe C, /. Mol. Struct. (Theochem) 507, 17 (2000). GregoireG., Brenner V., Millie" Ph., /. Phys. Chem. A 104, 5204 (2000). Le Barbu K., Brenner V., Millie" Ph., Lahmani F., Zehnacker-Rentien A., /. Phys. Chem. A 102, 128 (1998). Levy B., Enescu M., /. Mol. Struct. 432, 235 (1998). Marguet S., Markovitsi D., Millie Ph., Sigal H., Kumar S., J. Phys. Chem. B 102, 4697 (1998). Markovitsi D., Marguet S., GaUos L.K., Sigal H., Millie Ph., Argyrakis P., Ringsdorf H., Kumar S., Chem. Phys. Lett. 306, 163 (1999). Millie" Ph., Langlet J., Berges J., Caillet J., Demaret J.Ph., /. Phys. Chem. B 103, 10883 (1999). Mons M., Dimicoli I., Tardivel B., Piuzzi P., Brenner V., Millie Ph., J. Phys. Chem. A 103, 9958 (1999). Tramer A., Brenner V., Millie" Ph., Piuzzi F., J. Phys. Chem. A 102, 2798 (1998a). Tramer A., Brenner V., Milli6 Ph., Piuzzi F., / Phys. Chem. A 102, 2808 (1998b). Uridat D., Brenner V., Dimicoli I., Le Calve" J., Milli6 Ph., Mons M., Piuzzi F., Chem. Phys. 239, 151 (1998). 92 IV SCIENTIFIC COMMUNICATION January 1998 - June 2000 Articles in refereed journals 95 Articles in proceedings 109 Book chapters 113 Invited conferences 115 Invited seminars 121 Oral communications 127 PhD Theses 135 Popularization articles 137 Patent 138 93 Articles in refereed journals 1998 Effect of SF6 addition in the laser synthesis offuller ene and soot from C<5# Nonadiabatic heating of a plasma produced by the ionization of a gas by a short intense laser pulse. Andreev N.E., Chegotov M.V., Veisman M.E., Auguste T., d'Oliveira P., Hulin S., Monot P., Faenov A.Ya., Pikuz T.A., Magunov A.I., Skobelev I.Yu., Rosmej F.B., Romanovskii M.Yu., 1998, JETP-Letters 68, 592. Can we rationalize the structure of small silicon-carbon clusters ? Bertolus M, Brenner V., Millie Ph., 1998, Eur. Phys. J. D 1,197. SÍ3N/SÍCN nanocomposites : influence of SiC precipitates on the creep behaviour. Besson J.L., Mayne ML, Bahloul-Hourlier D., Goursat P., 1998, J. Eur. Cer. Soc. 18, 1893. Temporal dependence of high-order harmonics in the presence of strong ionisation. Bouhal A., Salières P., Breger P., Agostini P., Hamoniaux G., Mysyrowicz A., Antonetti A., Muller H.G., 1998, Phys. Rev. A 58, 389. Rayleigh scattering of laser and synchrotron radiation from pulsed jetof(Ar)„ and(N2O)„ clusters. Bush A.M., Bell A.J., Frey J.G., Mestdagh J.M., 1998, J. Phys. Chem. A 102, 6457. Reabsorption of light by trapped atoms. Castin Y., Cirac J.I., Lewenstein M., 1998, Phys. Rev. Lett. 80, 5305. Laser-induced non-sequential double ionization of small molecules. Cornaggia C, Hering Ph., 1998, J. Phys. В 31, L503. The Super-ACO FEL operation with shorter positron bunches. Couprie M.E., Nutarelli D., Roux R., Nation L., Visentin В., Delboulbé A., Flynn G., Billardon M., 1998, Nucl. Inst. Meth. A 407, 215. Implementing storage ring free electron laser for users on synchrotron radiation facilities : from super-ACO to SOLEIL. Couprie M.E., Nutarelli D., Billardon M., 1998, Nucl. Instr. Meth. В 144, 66. Quantum effects in the threshold photoionization and energetics of the benzene-НгО and benzene-DjO complexes : experiment and simulation. Courty A., Mons M., Dimicoli I., Piuzzi F., Gaigeot M.P., Brenner V., de Pujo P., Millie Ph., 1998, J. Phys.Chem. A102, 6590. Ionization, energetics and geometry of the phenol-S complexes (S=H2O, CH3OH and CH3OCH3). Courty A., Mons M., Dimicoli I., Piuzzi F., Brenner V., Millie Ph., 1998, J. Phys. Chem. A 102, 4890. Storage ring FEL dynamics and head-tail instability. Dattoli G., Mezi L., Renieri A., Migliorati M., Couprie M.E., Roux R., Nutarelli D., Billardon M., 1998, Phys. Rev. E 58, 6570. Solvation structure of coumarin I in acetonitrile: Role of the electrostatic solute-solvent potential. Diraison M., Millie Ph., Pommeret S., Gustavsson T., Mialocq J.C., 1998, Chem. Phys. Lett. 282, 152. 95 Characteristic features of the x-ray spectra of a plasma produced by heating C02 clusters by intense femtosecond laser pulses with 1=0.8 and 0.4mm Dobosz S., Schmidt M, Perdrix M., Meynadier P., Gobert O., Normand D., A. Ya. Faenov, A.I. Magunov, T.A. Pikuz. I.Yu. Skobelev, N.E. Andreev, 1998, J.E.T.P Letters 68,485. + Photofragmentation ofhydrated iron ions Fe(H2O) „ (n=l-9) at 532, 355, and 266 nm Dukan L., del Fabbro L.. Pradel P., Sublemontier O.. Mestdagh J.M., Visticot J.P., 1998, Eur. Phys. J. D 3, 257. Wave packet dynamics with Bose-Einstein condensates. Dum R., Sanpera A., Suominen K.A., Brewczyk M., Kus M., Rzcazewski K., Lewenstein M., 1998, Phys. Rev. Lett. 80, 3899. Infrared electron photo emission from a gold surface. Farkas G., Toth C, Kohazi-Kis A., Agostini P., Petite G., Martin P., Berset J.M., Ortega J.M., 1998, J. Phys. B31.L461. Configuration-interaction Hartree-Fock calculations for two-electron atoms using a pseudopotential. Féret L., Pascale J., 1998, Phys. Rev. A 55, 3585. Two-photon double-resonant excitation of the Xe* 5p5nf (J=2) autoionization states using synchronized laser and synchrotron radiation pulses. Gisselbrecht M., Marquette A., Meyer M., 1998, J. Phys. В 31, L977. Femtosecond dynamics of " TICT " state formation in small clusters : the dimethylaminobenzomethyle ester- acetonitrile system. Grégoire G., Dimicoli I., Mons M., Dedonder-Lardeux C, Jouvet C, Martrenchard-Barra S., Solgadi D., 1998, J. Phys. Chem. A 102, 7896. Is Nal soluble in water clusters ? Grégoire G., Mons M., Dimicoli I., Dedonder-Lardeux C, Jouvet C, 1998, Eur. Phys. J. D 1, 5. Photoionization of Nal : inward-outward asymmetry in the wavepacket detection. Grégoire G., Mons M., Dimicoli I., Piuzzi F., Charron E., Dedonder-Lardeux C, Jouvet C, Martrenchard- Barra S., Solgadi D., Suzor-Weiner A., 1998, Eur. Phys. J. D 1, 187. Real time monitoring of the evaporative cooling : an evaporation can hide an other one. Application to the dynamics ofNaI-(NH3)n clusters. Grégoire G., Mons M., Dimicoli L, Charron E., Dedonder-Lardeux C, Jouvet C, Martrenchard-Barra S., Solgadi D., 1998, J. Chem. Phys. 110,1521. Excitation processes for the emission of the unidentified IR bands. Guillois O., Ledoux G., Nenner I., Papoular R., Reynaud C, 1998, Far. Disc. 109, 335. Laser induced intrinsic defects : subpicosecond study of trapping kinetics. Guizard S., Itoh C, Martin P., d'Oliveira P., Meynadier P., Perdrix M., Petite G., 1998, Nucí. Instr. Meth. В 141, 66. Time-resolved fluorescence spectroscopy of high-lying electronic states of Zn-tetraphenylporphyrin. Gurzadyan G., Tran-Thi Т.Н., Gustavsson T., 1998, J. Chem. Phys. 108, 385. Femtosecond spectroscopic study of relaxation processes of three amino-substituted coumarin dyes in methanol and dimethylsulfoxide. Gustavsson T., Cassara L., Gulbinas V., Gurzadyan G., Mialocq J.C., Pommeret S., Sorgius M., Van Der Meulen P., 1998, J. Phys. Chem. A 102, 4229. 96 Neutral dissociation of hydrogen following photoexcitation of H Cl at the chlorine K-edge. Hansen D.L., Arrásate M.E., Cotter J., Fisher G.R., Leung K.T., Levin J.C., Martin R., Neill P., Perera R.C.C., Sellin I.A., Simon M., Uehara Y., Vanderford В., Whitfield S.B., Lindle D.W., 1998, Phys. Rev. A 57, 2608. Postcollision-interaction effects in HCl following photofragmentation near the chlorine K-edge, Hansen D.L., Armen G.B., Arrásate M.E., Cotter J., Fisher G.R., Leung K.T., Levin J.C., Martin R., Neill P., Perera R.C.C., Sellin I.A., Simon M., Uehara Y., Vanderford В., Whitfield S.B., Lindle D.W., 1998, Phys. Rev. A 57, R4090. Photofragmentation of third-row hydrides following photoexcitation at deep-core levels. Hansen D.L., Arrásate M.E., Cotter J., Fisher G.R., Hemmers О., Leung K.T., Levin J.C., Martin R., Neill P., Parera R.C.C., Sellin I.A., Simon M., Uehara Y., Vanderford В., Whitfield S.B., Lindle D.W., 1998, Phys. Rev. A 58, 3757. Production ofmulticharged atomic ions from laser-induced multiple ionization of small molecules. Hering Ph., Cornaggia C, 1998, Phys. Rev. A 57, 4572. Nanoparticles produced by laser pyrolysis of hydrocarbons: analogy with carbon cosmic dust. Herlin N., Bohn I., Reynaud C, Cauchetier ML, Galvez A., Rouzaud J.N., 1998, A&A 330, 1127. Photoabsorption by an ion immersed in a plasma at any temperature. Ishikawa K., Felderhof B.U., Blenski T., Cichocki В., 1998, J. of Plasma Phys. 60, 787. High-flux and high-resolution spectroscopic facility in the VUV region at Super-ACO. Ito K.r Lagarde В., PolackF., Alcaraz C, Nahon L., 1998, J. Synch. Rad. 5, 839. New spectroscopic results in Kr VIII. Jacquet E., Boduch Ph., Chantepie M., Lauhlé С, Lecler D., Pascale J., Wilson M., 1998, Physica Scripta 58, 570. Femtosecond fluorescence spectroscopy of self-trapped charge-transfer excitons in films of dimethylaminobenzylidene 1,3-indandione (DMABI). Jursemas S., Gulbinas V., Gustavsson T., Mialocq J.C., Valkunas L., 1998, Lietuvos Fizikos Zurríalas 38, 53. Optical properties of nanocrystalline silicon thin films produced by size-selected cluster beam deposition. Laguna M. A., Paillard V., Kohn В., Ehbrecht M., Huisken F., Ledoux G., Papoular R., Hofmeister H., 1998, Journal of Luminescence 80, 223. Triarylpyrylium salts : dynamics of the monomer-dimer equilibrium via a triplet absorption study. Lampre I., Markovitsi D., Sharonov A., Veber M., 1998, Chem. Phys. Lett. 293,423. High-order harmonic generation and quasiphase matching in xenon using self-guided femtosecond pulses. Lange H.R., Chiron A., Ripoche J.F., Mysyrowicz A., Breger P., Agostini P., 1998, Phys. Rev. Lett. 81, 1611. An experimental and theoretical study of jet-cooled complexes of chiral molecules: the role of dispersive forces in chiral discrimination. Le Barbu К., Brenner V., Millie Ph., Lahmani F., Zehnacker-Rentien A., 1998, J. Phys. Chem. A 102, 128. Beam-quality measurement of a focused high-order harmonic beam. Le Dé-roff L., Salières P., Carré В., 1998, Opt, Lett. 23, 1544. Silicon as a candidate carrier for ERE. Ledoux G., Guillois O., Huisken F., Laguna M.A., Nenner L, Paillard V., Papoular R., Porterat D., Reynaud С, 1998, A&A 333, L39. 97 Measurement of electric transition dipole moment using intracavity near resonant propagation in atomic vapours. LHermite D.. Comte M., Gobert О., de Lamare J„ 1998, Opt. Commun. 155, 270 Explosion dynamics of rare gas clusters in strong laser fields. Lezius M., Dobosz S., Normand D., Schmidt M., 1998 Phys. Rev. Lett. 80, 261. Interfacial carrier dynamics of cadmium sulfide nanoparticles. Logunov S., Green T., Marguet S., El-Sayed M.A., 1998, J. Phys. Chem. A 102, 5652. Influence of disorder on electronic excited states : An experimental and numerical study of alkylthiotriphenylene columnar phases. Marguet S., Markovitsi D., Millie Ph., Sigal H., Kumar S., 1998, J. Phys. Chem. В 102, 4697. Surface photovoltage in semiconductors under pulsed optical excitation and its relevance to synchrotron radiation spectroscopy. Marsi M., Nation L., Couprie M.E., Garzella D., Hara T., Bakker R., Billardon M., Delboulbé A., Indlekofer G., Taleb-Ibrahimi A., 1998, J. Electr. Spectr. Rel. Phen. 94, 149. Reactivity of vinyl chloride ionic clusters. Martrenchard-Barra S., Dedonder-Lardeux C, Dimicoli L, Grégoire G., Jouvet С, Solgadi D., 1998, Chem. Phys. 239, 331. Thermal behaviour ofSiCN nanopowders issued from laser pyrolysis. Mayne M., Bahloul-Hourlier D., Doucey В., Goursat P., Cauchetier M., Herlin N., 1998, J. Eur. Cer. Soc. 18, 1187. SijN4/SiCN nanocomposites : tensile ductility and rupture behaviour. Mayne M., Rouxel T., Bahloul-Hourlier D., Besson J.L., 1998, J. Eur. Cer. Soc. 18,1985. Absorption spectroscopy of a radiatively-heated samarium plasma, Merdji H., Missalla T., Blenski T., Perrot F., Gauthier J.C., Eidmann К., Chenais-Popovics С, 1998, Phys. Rev.E 57, 1042. Photodissociation dynamics of Ch in a xenon cluster. Mestdagh J.M., Berdah M., Auby N., Dedonder-Lardeux C, Jouvet C, Martrenchard-Barra S., Solgadi D., Visticot J.P., 1998, Eur. Phys. J. D 4, 291. Site-selective photochemistry of core excited molecules: role of the internal energy. Miron C, Simon M., Leclercq N., Hansen D.L., Morin P., 1998, Phys. Rev. Lett. 81,4104. Resonant Auger spectroscopy on SiF4 and SiCU molecules excited around the silicon 2p edge. Miron C, Guillemin R., Leclercq N., Morin P., Simon M., 1998, J. Electr. Spectr. Rel. Phen. 93, 95. Electron/Ion spectroscopy: aprobé of molecular dynamics. Morin P., Simon M., Miron C, Leclercq N., Hansen D.L., 1998, J. Electr. Spectr. Rel. Phen. 93,49. A new VUV high-resolution undulator-based beamline at Super-ACO. Nahon L., Lagarde В., Polack F., Alcaraz С Dutuit O., Vervloet M., Ito K., 1998, Nucl. Instr. Meth. A 404, 418. OPHÉLIE : a variable polarization electromagnetic undulator optimized for a VUV beamline at Super-ACO. Nahon L., Corlier M., Peaupardin P., Marteau F., Marcouillé O., Alcaraz С, 1998, J. Synch. Rad. 5,428. Gamma-rays produced by Compton back scattering of the Super-ACO free electron laser. Nutarelli D., Couprie M.E., Nahon L., Bakker R., Delboulbé A., Roux R., Visentin В., Billardon M., 1998, Nucl. Instr. Meth. A 407,459. 98 Silicon carbide and the 11.3 p.m. feature. Papoular R., Cauchetier M., Begin S., Le Caer G., 1998, A&A 329, 1035. Photoinduced electron transfer in jet cooled molecular complexes. Piuzzi F., Uridat D., Dimicoli I., Mons M., Tramer A., Le Barbu К., Lahmani F., Zehnacker-Rentien A., 1998, Acta Physica Polonica A 95,121. Analysis of correlation effects in autoionizing doubly excited states of barium using Coulomb Green's function. Poirier M., Semaoune R., 1998, J. Phys. В 31, 1443. Ultrafast events in the electron photodetachment from the hexacyanoferrate (II) complex in solution. Pommeret S., Naskrecki R., Van Der Meulen P., Ménard M., Vigneron G., Gustavsson T., 1998, Chem. Phys. Lett. 288, 833. Generation of attosecond pulse trains during the reflection of a very intense laser on a solid surface. Plaja L., Roso L., Rzazewski K., Lewenstein M., 1998, J. Opt. Soc. Am. В 15, 1904. High current operation of storage ring free electron laser. Roux R., Couprie M.E., Bakker R.J., Garzella D., Nutarelli D., Nahon L., Billardon M., 1998, Phys. Rev. E. 58, 6584. Temporal and spectral tailoring of high-order harmonics. Salières P., Antoine Ph., de Bohan A., Lewenstein ML, 1998, Phys. Rev. Lett. 81, 5544. Effects of heat treatment on the electronic structure of nanometric Si/C/N powders by X-ray photoélectron spectroscopy. Sénémaud С, Gheorghiu de la Rocque A., Dufour G., Herlin N., 1998, J. Appl. Phys. 84, 4945. Spectroscopic techniques using synchrotron radiation and free electron and conventional lasers. Tadjeddine Peremans A., Le Rille A., Zheng W.Q., Ortega J.M., Glotin F., Prazerez R., Meyer M., Lacoursière J., Nahon L., Gisselbrecht M., Morin P., Larzillière M., Marsi M., Taleb-Ibrahimi A., Couprie M.E., HaraT., Garzella D., 1998, J. Synchr. Rad. 5, 293. Early stages of the pyrolytic crystallization in amorphous nano-powders of silicon carbonitrides SixCyNz by combined high X-ray and neutron diffractometry. Ténégal F., Bouchet В., Bellissent R., Herlin N.. Cauchetier M., Dixmier J., 1998, Philosophical Magazine A 78, 803. Characterization of photo-induced electron transfer in jet-formed acceptor-donor complexes : I-Isomeric forms of the complexes of anthracene with aniline derivatives. Tramer A., Brenner V., Millie Ph., Piuzzi F., 1998, J. Phys. Chem. A 102, 2798. Characterization of photo-induced electron transfer in jet-formed acceptor-donor complexes : H-Photo- induced electron transfer : rates and mechanisms. Tramer A., Brenner V., Millie Ph., Piuzzi F., 1998, J. Phys. Chem. A 102, 2808. Existence of two internal energy distributions in jet-formed van der Waals heteroclusters : example of the anthracene-(argon)„ system. Uridat D., Brenner V., Dimicoli I., Le Calvé J., Millie Ph., Mons M., Piuzzi F., 1998, Chem. Phys. 239, 151. 99 1999 First polarization measurements of OPHELIE : a versatile polarization VUV undulator at Super-ACO. Alcaraz C, TMssen R., Compin M., Jolly A, Drecher M., Nahon L., 1999, Proc. SPIE 3773, 250. Characterization of a high-density large scale pulsed gas jet for laser-gas interaction experiments. Auguste T., Bougeard M., Caprin E., d'Oliveira P., Monot P., 1999, Rev. Sei. Instrum. 70, 2349. Velocity dependence of the emitted light polarisation following single electron capture for the Kr8+ Li(2s) collision system between 0.1 and 3 keV/amu. Boduch Ph., Chantepie M., Cremer G., Jacquet E., Kucal H., LauMé С, Lecler D., Pascale J., 1999, Physica Scripta T 80, 364. On the influence of RRC and RSC dimerizations on the shape of semi-integrated voltammograms : a mixed asymptotic and numerical analysis. Bureau Ch., Soudan J.M., Lecayon G., 1999, Electrochimica Acta 44, 3303. Laser pyrolysis of hydrocarbons in synthesis of soot containing fuller enes. Cauchetier M., Armand X., Herlin N., Alexandrescu R., Morjan I., Petcu S., Voicu I., 1999, Fullerene Science and Technology 7, 91. Si/C/N nanocomposite powders with Al (and Y) additives obtained by laser spray pyrolysis of organometallic compounds. Cauchetier M., Armand X., Herlin N., Mayne M., Fusil S., Lefevre E., 1999, J. Mat. Sei. 34,1. Effects of excess carbon and vibrational properties in ultrafine SiC powders. Charpentier S., Kassiba A., Bulou A., Monthioux M, Cauchetier M., 1999, European Physical Journal Applied Physics 8, 111. Investigation of the paramagnetic centres and electronic properties of silicon carbide nanomaterials. Charpentier S., Kassiba A., Emery J., Cauchetier M., 1999, J. Phys. С 11,4887. Optimizing high harmonic generation in absorbing gases -.model and experiment. Constant E., Garzella D., Breger P., Mevel E., Dorrer Ch., Leblanc С, Salin F., Agostini P., 1999, Phys. Rev. Lett. 82, 1668. Gamma-rays produced by intra-cavity Compton back scattering of a storage ring free electron laser. Couprie M.E., Nutarelli D., Roux R., Visentin В., Nahon L., Bakker R., Delboulbé A., Billardon M., 1999, J. Phys. В 32, 5657. Short wavelength free electron laser source. Couprie M.E. in "Les nouvelles sources ultra-brèves de rayons X et leurs applications", 1999, édité par J. C. Gauthier, Numéro Spécial des Comptes Rendus de l'Académie des Sciences. Interdependence of the electron beam excitations with the FEL stability on the Super-ACO storage ring. Couprie M.E., Roux R., Nutarelli D., Renault E., Billardon ML, 1999, Nucl. Instr. Meth. A 429, 165. Laser à electrons libres. Couprie M.E., Mosnier A., Ortega J.M., Nenner I., 1999, Actes de l'Académie des Sciences. Storage ring free electron laser and longitudinal instabilities experiments. Couprie M.E., 1999, Nuovo Cimento A112, 475. Laser UV à électrons libres. Couprie M.E., 1999, J. de Phys. IV 9, Pr5. 100 Methanol-acetonitrile complexes trapped in argon and nitrogen matrices : infrared induced isomerization and theoretical calculations. Coussan S., Bouteiller Y., Perchard J.P., Brenner V., Millie Ph., Zheng W.Q., Talbot F., 1999, J. Chem. Phys. 110, 20. A new method for deriving atomic charges and dipoles for n-alcanes : investigation of transferability and geometry dependence. Delhommelle J., Granucci G., Brenner V., Milli6 Ph., Boutin A., Fuchs A.H., 1999, Mol. Phys. 97, 117. Observation of ionswith energies above 100 keV produced by the interaction of a 60 fs laser pulse with clusters. Dobosz S., Schmidt M., Perdrix M., Meynadier P., Gobert O., Normand D., Ellert C, Blenski T., Faenov A., Magunov A.I., Pikuz T.A., Skobelev I., Andreev N.E., 1999, J.E.T.P. vol. 88, 1122. Study of the multicharged ion Ar6+ by a configuration-interaction Hartree-Fock method using a pseudopotential. Feret L., Pascale J., 1999, J. Phys. B 32,4175. Local structure of pre-alloyed Al/Y/SiCN nanopowders studied by XAS at the Al-K edge using fluorescence yield detection. Flank A.M., Armand X., Cauchetier M., Mayne M, 1999, J. Synch. Rad. 6, 512. Base specific photocleavage ofDNA induced by pazelliptine sensitization. Fontaine-Aupart M.P., Renault E., Videlot C, Tfibel F., Pansu R., Charlier M., Pernod P., 1999, Photochem. Photobiol. 70, 829. Influence of molecular oxygen on the charge transfer properties of a Co(II)porphyrin-Al(III)phthalocyanine aggregate. Excited states dynamics and photobiological activities. Fournier T., Tran-Thi T.H., Liu Z., Houde D., Brasseur N., La Madeleine C, Langlois R., Van Lier J.E., Lexa D., 1999, J. Phys. Chem. A 103, 1179. Cluster Isolated Chemical Reactions : Medium effects on reactivity. Gaveau M.A., Gee C, Mestdagh J.M., Visticot J.P., 1999, Comments At. Mol. Phys. 34, 241. Atom-Atom correlations induced by resonant coupling with a laser field. Gontier Y., 1999, Phys. Rev. A 59, 4747. Infrared ion-dip spectroscopy of a noradrenaline analogue : hydrogen bonding in 2-amino 1-phenyl ethanol and its singly hydrated complex. Graham R.J., Kroemer R., Mons M., Robertson E.G., SnoekL.C, Simons J.P., 1999, J. Phys. Chem. A 103, 9706. Diamond infrared emission bands in circumstellar media. Guillois O., Ledoux G., Reynaud C, 1999, The Astrophysical Journal 521, L133. Charge transfer induced twisting ofN,N-dimethylaminobenzylidene-l,3-indandione in solution. Gulbinas V., Kodis G., Jursenas S., Valkunas L., Gruodis A., Mialocq J.C., Pommeret S., Gustavsson T., 1999, J. Phys. Chem. A 103, 3969. Multi-Ion Coincidence Measurements of Methyl Chloride Following Photofragmentation Near the Chlorine K-Edge. Hansen D.L., Cotter J., Fisher G.R., Leung K.T., Martin R., Neill P., Perera R.C.C., Simon M., Uehara Y., Vanderford B., Withfield S.B., Lindle D.W., 1999, J. Phys. B 32, 2629. Coulomb explosion o/W2 and CO2 using linearly and circularly polarized femtosecond laser pulses. Hering Ph., Cornaggia C, 1999, Phys. Rev. A 59, 2836. 101 Silicon carbide nanoparticles produced by C02 laser pyrolysis ofSÍH4/C2H2 gas mixtures in a flow reactor. Huisken F., Kohn В., Alexandrescu R., Cojocaru S., Crunteanu A., Reynaud C, Ledoux G., 1999, J. Nanopart. Res. 1, 293. State-selective electron capture following Kr8+ - Li(2s) collisions for impact energies from 0.1 to 1.5 keV/amu. Jacquet E., Chantepie M., Boduch Ph., Lauhlé С, Lecler D., Pascale J., 1999, J. Phys. В 32,1151. Usefulness of X-ray lasers for science and technology. Jamelot G., Carillon A., Jaegle P., Klisnick A., Ros D., Zeitoun P., Fourcade P., Hubert S., Lagron J.C., Vanbostal L., Sebban S., Albert F., Agostini P., Garzella D., Brega P., Belsky A., Kamenskikh I., Joyeux D., Phalippou D., Boussoukaya M., Zeitoun- Fakiris A., de Lacheze-Murel G., Bechir E., 1999, ШЕЕ J. Sel. Top. Quan. Elec. 5, 1486. Demonstration of two color transient pumping in Ni like silver at 13.9 nm and 16.1 nm. 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Proton-transfer reaction in the ground state of phenol-ammonia clusters : an experimental study. Martrenchard-Barra S., Dedonder-Lardeux C, Jouvet C, Solgadi D., Vervloet M., Grégoire G., Dimicoli L, 1999, Chem. Phys. Lett. 310,173. Internal energy of photofragments studied by dispersed fluorescence spectroscopy. Meyer M., Marquette A., Gisselbrecht M., 1999, J. Electr. Spectr. Rel. Phen. 101, 81. Spectroscopie laserfemtoseconde dans l'eau, milieu biologique. Mialocq J.C., Gustavsson T., Pommeret S., 1999, J. de Phys. IV 9, Pr5, 101. Self-association of amphotericin В in water. Theoretical energy and spectroscopy studies. Millie Ph., Langlet J., Berges J., Caillet J., Demaret J.Ph., 1999, J. Phys. Chem. B 103,10883. Conformations of 2-phenylethyl alcohol and of its singly hydrated complexes : UV and IR/UV ion-dip spectroscopy. Mons M., Robertson E.G., SnoekL.C, Simons J.P., 1999, Chem. Phys. Lett. 310,423. 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Air Pollution, 2000 (sous presse). 110 18tK International Conference on X-ray and Inner-Shell Processes, Chicago, Etats-Unis, 23-27 Aout 1999. Charge exchange induced X-ray transitions of hollow ions in laser field ionized plasmas. Rosmej F.B., Hoffmann D.H.H., Faenov A.Ya., Pikuz T.A., Magunov A.I., Skobelev I.Yu., Auguste T., d'Oliveira P., Hulin S., Monot P. Dynamical effects and selective fragmentation after inner shell excitation. Simon M., Miron C, Guillemin R., Le Guen K., Ceolin D., Shigemasa E., Leclercq N., Morin P. AIP Conference Proceedings 2000. The 1999 International Conference on Strongly Coupled Coulomb Systems, Saint-Malo, France, 4-10 September 1999. Electronic structure and statistical mechanics of ionic configurations in hot plasmas. PerrotF.,BlenskiT. Proceeding of the Conference, 2000, (sous presse). IFSA, Bordeaux, France, 12-17 Septembre 1999. The ASTROLABE 1 experiment: Rayleigh-Taylor instabilities in supernovae. Baclet Ph., Benuzzi-Mounaix A., Bouquet S., Cherfils C, Chieze J.P., Mucchielli F., Munsch P., Poles L., Reverdin Ch., Teyssier R., Thais F., Thgbault J.P. Troussel Ph. Investigation of fast ions and hot electrons in laser produced plasmas by means of high resolution X-ray spectroscopy. Rosmej F.B., Hoffmann D.H.H., SUB W., GeiBel M., Faenov A.Ya., Skobelev I.Yu., Magunov A.I., Pikuz T.A., Bock R., Letardi T., Flora F., Bollanti S., Di Lazzaro P., Satov Yu. A., Smakovskii Yu. B., Stepanov A.E., Roerich V.K., Khomenko S.V., Nischuk S., Makarov K.N., Reale A., Scafati A., Auguste T., d'Oliveira P., Hulin S., Monot P., Sharkov B.Y. X rays absorption in dense plasmas, Theory versus Experiment. Blenski T., Perrot F., Renaudin P., Chenais-Popovics C, Fajardo M., Merdji H., Gilleron F., Gauthier J.C., Eidmann K., Andiel U. Proceedings published in Inertial Fusion Sciences and Applications 99, C. Labaune, W. J. Hogan and K. A. Tanaka Eds., Elsevier, Paris. 16lh International Conference on Magnet Technology, Ponte Verta Beach, Etats-Unis, 26 septembre - 2 Octobre 1999. Performances of OPHELIE: a new type of undulator at LURE. Marteau F., Corlier M., Besson J.C., Brunelle P., Claverie J., Godefroy J.M., Herbeaux C, Lefebvre D., Marcouille' O., Marlats J.L., Marx J. P., Peaupardin P., Petit A., Sommer M., Veteran J. Nation L. Transactions on Applied Superconductivity 10-1 (2000) 8th International Conference on Multiphoton Processes , Monterey, Etats-Unis, 3-8 Octobre 1999. Applications of high-order harmonic generation. Descamps D., Norin J., Lynga C, Buil S., l'Huillier A., WahlstrOm C.G., Sorensen S.L., Bjorneholm O., Gisselbrecht M., Meyer M., Hergott J.F., Merdji H., Salieres P., Bellini M. High order harmonic generation : A coherent ultrashort emission in the XUV range. Salieres P., Hergott J.F., Mardji H., le Deroff L., Cam* B., Auguste T., Monot P., d'Oliveira P., Joyeux D., Phalippou D. ATP Conference Proceeding 2000. Workshop "Perspectives on Atomic and Molecular Physics with a 30 Meters long Undulator", Spring 8, Japon, 6-7 Decembre 1999. Relaxation dynamics of core excited molecules. Simon M., Miron C, Leclercq N., Morin P. Proceeding 2000 (sous presse). Ill 15eme Congres Franc.ais sur les Aerosols, Paris, France, 8-9 Decembre 1999. Utilisation et etude d'un generateur d'aerosols pour la synthese de poudres ceramiques nanometriques. Mayne M.. Allain N., Armand X., Herlin-Boime N., Cauchetier M. Proceeding dans J. of Aerosol Science (sous presse). 5*me Colloque sur les Sources Coherentes et Incoherentes UV, VUV et X. Applications et Developpements Recents, He de Porquerolles, France, 16-19 Mai 2000. Etude du front d'onde des nouvelles sources XUV. Le Pape S., Zeitoun Ph., Carre" B., Dhez P., Francois M., Hergott J.F., Idir M., Merdji H., Salieres P. Proceeding 2000 (sous presse). Organic-Inorganic hybrids : Science, Technology and Applications, Guilford, Royaume-Uni, 12-14 Juin 2000. Monocyclic aromatic hydrocarbon sensors based on sol-gel material. Calvo-Munoz M.L., Tran-Thi T.H., Roux C, Bourgoin J.P., Ayral A., El-Mansoun A. PRA Proceedings, Organic-Inorganic Hybrids, (2000) 112 Book chapters Rusek M., Qrlowski A. Localization of light in three-dimensional disordered dielectrics. Chapitre du livre: Optics of Nanostructured Materials, edited by Vadim A., Markel V. and Thomas F. (John Wiley & Sons, Ltd., New York), 2000, to be published. Salieres P., L'Huillier A., Antoine Ph., Lewenstein M. Study of the spatial and temporal coherence of high-order harmonics. Chapitre du livre: Adv. Atom, Molec. Opt. Phys. 41, 83. edited by Bederson B. and Walther H. (Academic Press ), 1999. Lezius M, Schmidt M. Experiments on laser-heated rare gas clusters. Chapitre du livre : Introduction to molecules and clusters in intense laser fields , Cambridge University Press., 2000, to be published. Soep B., Mestdagh J.M. Electron-transfer reactions involving atoms, molecules and clusters. Chapitre du livre: Handbook of Election Transfer, edited by Haas Y. (John Wiley & Sons, Ltd., New York), 2000, to be published. 113 Invited conferences Agostini P. Circular dichroism in two-photon two-color ionization of atoms. Ultra-intense Laser Interaction and Applications I, Elounda, Grece, Mai 1999. Agostini P. Ponderomotive shift and cross-correlation measurements of XUVpulses. Journ63S NSF-CNRS, Laboratoire d'Optique Appliquee, Ecole Polytechnique, Palaiseau, France, Juin 1999. Agostini P. Atoms in intense and super-intense laser fields. Annual Meeting of the European Physical Society, Londres, Royaume-Uni, Septembre 1999. Agostini P. Presentation generale de {'interaction laser-matiere. JECAM, Saclay, France, 17 Janvier 2000. Blenski T. Quelques remarques sur les opacites theoriques. Atelier- " Vers une Astrophysique Experimentale aupres des Grands Lasers ", Meudon, France, 9-10 Novembre 1998. Blenski T. X-ray absorption in dense plasmas. Atelia-" Intense Laser Fields: X-Ray Generation and Applications", Les Houches, France, 8-11 Mars 1999. Breger P. High harmonic generation and quasi-phase matching with self-guided femtosecond laser pulses. Ultrafast Phenomena, Garmish-Partenkirchen, Allemagne, 11-17 Juillet 1998. Carre" B. Generation d'harmoniques laser dans les gaz : principals caracteristiques et premieres applications. Journees " DeVeloppement et Applications des Sources XUV Intenses et Breves ", University Paris XI, Orsay, France, 5-6 Mars 1998. Cam* B. High-order harmonic generation : An XUV source in the femtosecond range. 12th International Conference on Vacuum Ultraviolet Radiation Physics, San Francisco, Etats-Unis, 3-7 Aout 1998. Carre'B. Temporal and spatial coherence of high order harmonics. 8th International Laser Physics Workshop (LPHYS'99), Budapest, Hongrie, 2-6 Juillet 1999. CamJB. Generation d'harmoniques d'ordre eleve dans les gaz. Journees " Optiques UVX ", CNRS, Paris, France, 25 Septembre 1999. Carr6B. La generation d'harmoniques d'ordre eleve: une source ultra-breve dans I'UVX. JECAM, Saclay, France, 17 Janvier 2000. Carre" B. Coherence properties of high harmonic generation and applications. 7th International Conference on X-Ray Lasers, Saint-Malo, France, 19-23 Juin 2000. 115 Cornaggia C. Laser-induced non-sequential double and multiple ionization of small molecules. 7th International Laser Physics Workshop (LPHYS'98), Berlin, Allemagne , 4-10 Juillet 1998. Couprie M. E. Implementing storage ring free electron lasers for users on synchrotron radiation facilities : from Super-ACO to SOLEIL. Free Electron Laser Facilities and Applications, Keihanna Plaza, Kyoto, Japon, Janvier 1998. Couprie M. E. Lasers a electrons libres sur anneaux de stockage de troisieme generation. Journeys " De"veloppement et Applications des Sources X et X UV Intenses et Breves ", University Paris XI, Orsay, France, 5-6 Mars 1998. Couprie M. E. Storage ring FEL and longitudinal instabilities. Workshop " Non Linear Problems in Charged Beam Transport in Linear and Recirculated Accelerators, Analysis of Transverse and Longitudinal Instabilities ", ENEA, Frascati, Italie, 13-15 Mai 1998. Couprie M. E. Laser UV a electrons libres. UVX98, Collonges-la-Rouge, France, 6 Octobre 1998. Couprie M. E. Overview of storage ring based FELs. Current Development on FELs, Lund, Suede, 18 Octobre 1998. Couprie M. E. Ring based FELs in the UV. Workshop " New Sources of Coherent X-rays", Aix-en Provence, France, 5 Juillet 1999. Couprie M. E. Are FEL's the fourth generation light sources? CERN Accelerator School, B6nodet, France, Septembre 1999. Couprie M. E. The Super-ACO FEL source. Workshop " Synchrotron Radiation", JINR, Dubna, Russie, 1-3 Novembre 1999. Dimicoli I. Structure and binding energy of organic molecule - water complexes. International Symposium on Molecular Clusters, Niederpocking by Munich, Allemagne, 25-29 Mai 1999. EllertC. Highly charged ions from rare gas and metal clusters in intense laser fields Ultra-Intense Laser Interaction and Application I, 7-11 Mai 1999, Elounda, Grece. Gaveau M.A, Reaction between barium and N2O on large neon clusters. 21eme International Symposium on Rarefied Gas Dynamics, Marseille, France, 26-31 Juillet 1998. Gre"goire G. Separation de charges dans les agregats Nal - Sn ; S=H2O, NH3, CH3CN. GDR Agr6gats, Carry Le Rouet, France, 25-27 Novembre 1998. Gr6goire G. La photoionisation par lasers femtoseconde: une sonde de la dynamique moleculaire. JECAM, Saclay, France, 17 Janvier 2000. 116 Marguet S. Transfert d'energie a I'etat singulet dans des cristaux liquides colonnaires. Lumieres sur les Systemes Mol£culaires Organises, Mulhouse, France, 10-12 Juin 1998. Markovitsi D. Electronic excited states and excitation transport in columnar liquid crystals. Annual Meeting of the British Liquid Crystal Society, Leeds, Royaume-Uni, 6-8 Avril 1998. Markovitsi D. Electronic excited states and excitation transport in columnar liquid crystals. Workshop of the D4 COST Action, Riva del Sole, Italie, 25-28 Avril 1998. Markovitsi D. Excitation transport in columnar liquid crystals. Workshop on Organic Semiconductors, Marburg, Allernagne, 29 Septembre-ler Octobre 1999. Merdji H. Interferometry using high-order harmonics: Application to high density laser plasma diagnostic. Workshop " Applications of High-Order Harmonics ", Lund, Suede, 17-18 Mars 2000. Merdji H. Nouvelles perspectives de diagnostics de plasmas denses par generation d'harmoniques. 5eme Colloque sur les Sources CoheYentes et Incohe'rentes UV, VUV et X. Applications et D6veloppements Recents, He de Porquerolles, France, 16-19 Mai 2000. Millie" Ph. Agregats moleculaires : de la structure a la rfactivite. GDR Agr6gats, Carry Le Rouet, France, 25-27 Novembre 1998. Millie" Ph. Methode de Car et Parrinello : raise en service dans le cos de petits agregats silicium-carbone. Journees " Simulation Numerique, Matiere Condensed et D£sordre ", 5eme Edition, Universit6 Paris VI, France, 8-9 Juin 1999. Structure des agregats moleculaires ionises. Energ&ique et R6activite" des Ions en Phase Gazeuse : Experience et The"orie (ERIG 99), Gif sur Yvette, France, 17-19 Novembre 1999. Mons M. Ion-dip spectroscopy of conformers andhydrated clusters. International Symposium on Molecular Clusters, Niederpocking by Munich, Allemagne, 25-29 Mai 1999. Mons M. Photoionisation laser de systemes moleculaires; photoexcitation de cations moleculaires: quelques exemples et applications. Energ&ique et Reactivite" des Ions en Phase Gazeuse : Experience et The'orie (ERIG 99), Gif sur Yvette, France, 17-19 Novembre 1999. Mons M. Energetics of hydrogen bonding in biomimetic molecules. Euroconference " Experimental Tools and Quantum Chemistry : Molecules of Biological Interest in the Gas Phase "„ Les Houches, France, 13-18 Mai 2000. Morin P. Le projet SOLEIL Colloque annuel de l'Association Francaise de Cristallographie, Orleans, France, 5-7 F6vrier 1998. 117 Morin P. Auger-ion coincidence spectroscopy applied to free molecules in the soft X ray regime. VUV 12, plenary session, San Francisco, Etats-Unis, 3-7 Aout 1998. Morin P. Photoionisation dissociative de molecules isolees. Ecole th£matique Temps-Position-Image, Orsay, France, 3-5 Novembre 1999. Nahon L. Applications of UV-storage ring free electron lasers : the case of Super-ACO. 20th international FEL 98 Conference and 5th FEL Users Workshop, Williamsburg, Etats-Unis, 16-21 Aout 1998. Nahon L. Potentialities offered by UV-storage ring FELs as a source for scientific applications. Low Energy Sources Workshop, Daresbury, Royaume-Uni, 5-6 Mars 1999. Nahon L. Performances obtenues sur la ligne SU5 de Super-ACO : une ligne VUV a haute resolution et a polarisation variable. UVX2000, He de Porquerolles, France, 16-19 Mai 2000. Nutarelli D. Complete characterisation of dielectric multilayers mirrors for performance improvement of free electron lasers. 20th FEL International Conference, Williamsburg, Etats-Unis, 16-21 Aoflt 1998. Pascale J. Approche CTMC aux collisions ions multicharges-atomes. Perspectives et difficultes d'application aux molecules. Atelier " Multi-ionisation et Instabilit6 de Molecules et d'Agr6gats ", Saclay, France, 12-13 Mars 1998. Piuzzi F. Photoinduced electron transfer in jet cooled molecular complexes. The Jablonski Centennial Conference, Torun, Pologne, 27-31 Juillet 1998. Piuzzi F. Characterization of electron transfer in anthracene clusters (n=l to 5). International Symposium on Molecular Clusters, Niederpocking by Munich, Allemagne, 25-29 Mai 1999. Piuzzi F. Photoinduced electron transfer in jet cooled anthracene clusters. Photoprocesses in Molecular Assemblies, Dourdan, France, 27-30 Juin 1999. Piuzzi F. New desorption-expansion method for generation of isolated cold biological molecule : application to the spectroscopy of ' triptophan. ALT '99, Potenza et Lecce, Italie, 19-24 Septembre 1999. Piuzzi F. New desorptiorv'expansion device for generation of isolated cold biological molecules : Application to the spectroscopy oftryptophan and guanine. International Conference on Photodynamics from Isolated Molecules to Condensed Phases, La Havane, Cuba, 14-19 Fevrier 2000. 118 Renault E. Perspective of the transient absorption spectroscopy: Ionization ofDNA components in aqueous solution. EMBO Workshop " Potential Future Applications in Structural Biology of an X-ray Free Electron Laser at DESY ", Hambourg, Allemagne, 4-8 Juillet 1999. Renault E. Photobiology by the transient absorption of different FEL-excited chromophoric compounds at the Super- ACO FEL. 6th FEE Users Workshop, Hambourg, Allemagne, 22-27 Aoilt 1999. Reynaud C. Present situation in the coal model for interstellar carbon dust. Les Houches School," Solid Interstellar Matter: The ISO Revolution", Les Houches, France, F6vrier 1998. Roux R. Storage ring free electron laser and coherent synchrotron oscillation : Simulation approach. Workshop " Non Linear Problems in Charged Beam Transport in Linear and Recirculated Accelerators, Analysis of Transverse and Longitudinal Instabilities ", ENEA, Frascati, Italic 13-15 Mai 1998. Salieres P. Generation d'harmoniques laser dans les gaz : principals caracteristiques et premieres applications. Journees " D6veloppement et Applications des Sources XUV Intenses et Breves ", University Paris XI, Orsay, France, 5-6 Mars 1998. Salieres P. Generation d'harmoniques d'ordre eleve. S6minaire "Interaction Laser-Matiere", Seignosse, France, 25-29 Mai 1998. Salieres P. Coherence properties of high-order harmonics and applications. Intense Laser Fields : X-ray Generation and Applications, Les Houches, France, 8-11 Mars 1999. Salieres P. High-order harmonic generation : a coherent ultrashort emission in the XUV. 8th International Conference on Multiphoton Processes, Monterey, Etats-Unis, 3-8 Octobre 1999. Salieres P. Introduction to high-order harmonic generation. Workshop " Applications of High-Order Harmonics", Lund, Suede, 17-18 Mars 2000. Salieres P. Source UVX coherente et ultrabr$ve par generation d'harmoniques d'un laser intense. 5iws Colloque sur les Sources Coherentes et Incoh&entes UV, VUV et X. Applications et D6veloppements r6cents, He de Porquerolles, France, 16-19 Mai 2000. Schmidt M. Clusters in strong laser fields. EC AMP 98, Siena, Italie 14-18 Juillet 1998. Schmidt M. Generation de rayons X durs par irradiation laser d'agregats de gaz rares. UVX 98, Collonges-la-Rouge, France, 5-9 Octobre 1998 Schmidt M. Generation de rayons Xpar irradiation laser d'agregats de gaz rares. S6minaire annuel du LULI, Seignosse, France, 24 Mai 1998. 119 Schmidt M. Cluster Beams in Strong Laser Fields. Intense Laser Fields : X-ray Generation and Applications, Les Houches, France, 8-11 Mars 1999. Schmidt M. Cluster explosion dynamics and X-ray generation from clusters in intense laser fields. Gordon Research Conferences on Multiphoton Processes, New Hampshire, Etats-Unis, 14-19 Juin 1998 Schmidt M. Atomic and Molecular Cluster Jets in Strong and Ultra-short Laser Fields. SYLF '99, Friihjahrstagung der DPG, Heidelberg, Allemagne, 14-19 Mars 1999 Schmidt M. High intensity laser/matter interactions. American Physical Society Centennial Meeting, Atlanta, Etats-Unis, 20-26 Mars 1999. Schmidt M. Clusters in Strong and Ultra-short Laser Fields, ICOMP 8, Monterey, Etats Unis, 3-10 octobre 1999. Schmidt M. Le projet PREUVE et le defi de la lithographie dans Vextreme ultraviolet 54me Colloque sur les Sources CoheYentes et IncoheYentes UV, VUV et X. Applications et D6veloppements r6cents, He de Porquerolles, France, 16-19 Mai 2000 Simon M. Perspectives for electron-ion spectroscopy of core excited molecules. Workshop " Perspectives on Atomic and Molecular Physics at MAX II", Uppsala, Suede, 9-10 Mars 1998. Simon M. Relaxation dynamics of core excited molecules. Workshop " Perspectives on Atomic and Molecular Physics with a 30 Meters long Undulator", Spring, Japon, 6-7 Decembre 1999. Simon M. Dynamical effects and selective fragmentation after inner shell excitation. 18th X-ray and Inner-Shell Processes, Chicago, Etats-Unis, 23-27 Aout 1999. Tran-Thi T.H. Excited state proton transfer from pyranine to water. What is the molecular pathway ? Research Workshop of the Israel Science Foundation" Proton Solvation and Proton Mobility ", Neve-Ilan, Israel, 18-22 Octobre 1998. Tran-Thi T.H. A strong internal electrical potential can reverse the direction of electron transfer. XIX International Conference on Photochemistry, Durham, North Carolina, Etats-Unis, 1-6 Aout 1999. Visticot J.P. Spectroscopy and reactivity of barium atoms and complexes on large neon clusters. Colloque Franco-Taiwanais " Dynamique Mol6culaire et Dynamique des Reactions Alcalin/Hydrogene ", Universitf Paris XI, Orsay, France,12-14 Octobre 1998. 120 Invited seminars Agostini P. Transitions a deux couleurs XUV-IR et applications. S6minaire du cours de C. Cohen-Tannoudji, College de France, Paris, France, 26 Octobre 1999. Carr6 B. Interaction laser matiere en champ fort au SPAM. DAM/CESTA, Bordeaux, France, 6 Decembre 1999. Cornaggia C. La covariance : une analyse statistique des signaux de multifragmentation. Ecole Th6matique " Defection, Temps, Position, Image ", University Paris XI, Orsay, France, 3-5 Novembre 1999. Couprie M.E. The Super-ACO free electron laser source. Kyoto University, Japon, 21 Janvier-3 Fe"vrier 1998. Couprie M.E. The Super-ACO free electron laser dynamics. Argonne Laboratory, Etats-Unis, 5-17 Avril 1999. Ellert Ch. Agregats en champ fort. Reunion preparatoire du GDR Agr6gats, Orsay, France, 17 Mai 1999. GrSgoire G. Separation de charges dans les agregats moleculaires. Laboratoire de Physico-Chimie des Rayonnements, Orsay, France, 5 Juin 1998. Gr6goire G. Separation de charges dans les agregats moleculaires : Dynamique et spectroscopie. Application au systeme Nal -(solvants polaires)n. Laboratoire de Photophysique Moleculaire, CNRS, Orsay, France, 25 Septembre 1998. Gustavsson T. Ultrafast relaxation processes of photoexcited triarylpyrylium cations. Institut fur Physikalische und Theoretische Chemie, Humboldt-Universitat, Berlin, Allemagne, 4 Octobre 1999. Hergott J.F. Proprietes optiques du rayonnement harmonique. Reunion GDR SAXO, University Paris VII, France, 9-10 Mars 2000. Hulin S. OFI X-ray laser scheme in H-like nitrogen. Reunion r&eau laser X europeen, Amesee, Allemagne, 8-9 Fevrier 1999. Hulin S. Laser X en recombinaison dans un jet d'azote ionise par effet de champ (OFI). Simulations numeriques et experiences. DAM/B3, Bruyeres le CMtel, France, 26 Novembre 1999. Hulin S. Soft X-ray laser scheme based on OFI. Reunion reseau laser X europeen, York, Royaume-Uni, 7-8 F6vrier 2000. 121 Ledoux G. La Photoluminescence des nanocñstaux de silicium.. Ecole Centrale de Lyon, France, 24 Mars 1998. Markovitsi D. Transfert d'énergie à l'état excité singulet dans des phases colonnaires. Université de Mons-Hainaut, Mons, Belgique, 22 Avril 1998. Markovitsi D. Excitation energy transfer in columnar liquid crystals. Université de Ioannina, Ioannina, Grèce, 19 Octobre 1998. Markovitsi D. Electronic excited states and energy transfer in columnar liquid crystals. Université d'Osaka, Osaka, Japon, 30 Novembre 1998. Markovitsi D. Electronic excited states and energy transfer in columnar liquid crystals. Institute for Molecular Science, Okazaki, Japon, 1 Décembre 1998. Merdji H. Génération de rayonnement X et applications. Centre Lasers Intenses et Applications, Bordeaux, France, 8 Février 1999. Merdji H. Applications interféromètriques des harmoniques d'ordre élevé au diagnostic de plasmas denses. Laboratoire pour l'Utilisation des Lasers Intenses, Ecole Polytechnique, Palaiseau, France, 9 Novembre 1999. Merdji H. Propriétés de cohérence de la génération d'harmoniques d'ordre élevé et applications. DAM/CESTA, Bordeaux, France, 6 Décembre 1999. Mestdagh J.M. Dynamique réactionnelle au contact de gros agrégats de van der Waals. Université Paris ХШ, Villetaneuse, France, 20 Novembre 1998. Mestdagh J.M. Comportement préréactionnel d'alcènes excités électroniquement. Université Paris XI, Orsay, France, 5 Mai 2000. Millié Ph. Calculs ab initio et modélisation. Journée Galilée "Modélisation-Interaction-Molécules Biologiques", Institut Galilée, Université Paris XIII, France, 17 Juin 1998. Millié Ph. Potentiels intermoléculaires et agrégats. Laboratoire de Physico-Chimie des Rayonnements, Université Paris XI, Orsay, France, 26 Juin 1998. Millié Ph. Méthodes de la fonctionnelle de la densité et agrégats : quelques résultats récents. Laboratoire des Collisions Atomiques et Moléculaires, Université Paris XI, Orsay, France, 9 Décembre 1998. Millié Ph. Les méthodes de la fonctionnelle de la densité : principe, réussites et échecs. Université de Bordeaux I, France, 22 Novembre 1999. 122 Mons M. Hydrogen-bonded complexes of jet-cooled organic molecules with water: structure and energetics. Physical and Theoretical Chemistry Laboratory, University of Oxford, Royaume-Uni, 26 Avril 1999. Mons M. Experimental binding energies of water to aromatic molecules : microscopic approach to the side chain of aromatic aminoacids. Department of Chemistry, University College, London, Royaume-Uni, 25 Juin 1999. Mons M. Spectroscopie infrarouge de molecules flexibles en phase gazeuse. Laboratoire de Photophysique Mol6culaire, CNRS, Orsay, France, 7 Janvier 2000. Mons M. Les liaisons hydrogene des molecules d'interet biologique : une approche en agregat. IRSAMC, Universit6 Paul Sabatier, Toulouse, France, 5 Juin 2000. Mons M. Hydratation de molecules flexibles en phase gazeuse. Service des Photons, Atomes et Mol6cules, Saclay, France, 19 Juin 2000. Nahon L. Synchrotron Radiation, Free electron lasers and conventional lasers : different and complementary photon sources, allowing the performance of multi-color experiments. AMOLF/FOM, Amsterdam, Pays-Bas, 10 Fe"vrier 1998. Nahon L. The SU5 high resolution/high flux VUV beamline with exotic polarizations at Super-ACO: Why ? How ? and first results. Photon Factory, s^minaire g6n6ral joint avec Electro-Technical Labs, Tsukuba, Japon, 26 Octobre 1998. Nahon L. La ligne SU5 de Super-ACO : une ligne VUV a haute resolution et polarisation variable pour la spectroscopie et le dichroisme. Centre de Biophysique Moteculaire, CNRS, Orleans, France, 31 Mars 2000. Normand D. Interaction dynamics of clusters in strong laser fields. Department of Chemistry Scholl of Science - Universite de Tokyo, Japon, jeudi 29 juin 2000. Nutarelli D. Le laser a electrons libres de Super-ACO, une source laser UV accordable performante pour les applications. Laboratoire des Collisions Atomiques et Mol&ulaires, University Paris XI, Orsay, France, 15 D6cembre 1999. Piuzzi F. Novel desorption method for vaporization of intact biomolecules; application to the gas phase spectroscopy oftryptophan and guanine and the guanine complex with water. Institut de Physique de la Matiere Condensed, University de Lausanne, Lausanne, Suisse, 7 Avril 2000. Poisson L. + + Proprietes spectroscopiques et collisionnelles des ions Fe(H2O)n et Co(H2O)n . Laboiratoire des M6canismes R6actionnels, Ecole Polytechnique, Palaiseau, France, 22 Fe"vrier 2000. de Pujo P. Dynamique moleculaire : application a Vetude de systemes moleculaires. Laboiratoire de Physico-Chimie des Rayonnements, Universal Paris XI, Orsay, France, 22 Janvier 1999. 123 de Pujo P. Spectres de vibration dans les agrégats de Van der Waals : Comparaison avec des calculs ab initio. Laboratoire de Chimie Physique des Matériaux Amorphes, Université Paris XI, Orsay, France, 25 Mars 1999. Renault E. Développement de l'absorption transitoire combinant le laser à électrons libres et le rayonnement synchrotron. Laboratoire pour l'Utilisation du Rayonnement Electromagnétique, Orsay, France, 19 Mars 1999. Reynaud C. Nanosolides carbonés modèles de la poussière interstellaire. Laboratoire de Spectrométrie Ionique et Moléculaire, Université Claude Bernard, Lyon, France, 18 Mars 1999. Reynaud С Les nanosolides modèles de la poussière cosmique. Groupe de Physique des Solides, Université Paris VI et VII, Paris, France, 27 Mai 1999. Reynaud C. Effets de taille dans les solides carbonés. Laboratoire des Collisions Atomiques et Moléculaires, Université Paris XI, Orsay, France, 16 Juin 1999. Roux R. Fonctionnement du laser à électrons libres de Super-ACO avec une cavité harmonique à 500 MHz. Laboratoire pour l'Utilisation du Rayonnement Electromagnétique, Orsay, France, 7 Juillet 1998. Salières P. Coherence properties of high-order harmonics. Lund Laser Center, Lund, Suède, 17 Mars 1999. Saueres P. Propriétés du rayonnement d'harmoniques d'ordre élevé et applications. DAM/B3, Bruyères-le-Châtel, France, 28 Février 2000. Schmidt M. Agrégats de gaz rares en champ laser intense. Laboratoire Aimé Cotton, Orsay, France, 14 Mai 1998. Schmidt M. Clusters in strong laser fields. Max Planck Institut für Quantenoptik (MPQ), Garching, Allemagne, 17 Novembre 1998 Schmidt M. Agrégats en champ fort. Réunion préparatoire du GDR Agrégats, Orsay, France, 17 Mai 1999. Schmidt M. X-ray generation from laser irradiation of cluster jets. Philips and ASM/L, Eindhoven, Pays Bas, 23 Juin 1999. Schmidt M. Agrégats en champ fort. CEA/DAM, Bruyères le Chatel, France, 28 Juin 1999. Schmidt M. Agrégats en champ fort. LASIM, Université Claude Bernard, Lyon, France, 1 Juillet 99. 124 Simon M. Techniques de coincidences. Ecole the'matique "Detection, Temps, Position. Image", Universit6 Paris XI, Orsay, France, 3-5 Novembre 1999. Thomas A.L. Potentiels modeles dans les systemes cation-molecules. Laboratoire de Chimie Physique, University Paris XI, Orsay, France, 26 Mai 2000. Tran - Thi T.H. Capteurs chimiques d'hydrocarbures aromatiques monocycliques. E.N.S. Cachan, Departement de Chimie, Cachan, France, 9 Juin 2000. 125 Oral communications Journées annuelles du Groupe Français de la Céramique (GFC), 3-4 Février 1998, Cadarache, France. Rôle d'une seconde phase nanométrique SiC(N) sur la densification et la microstructure de nanocomposites SÍ3N4/SÍQN). Mavne M. , Bahloul-Hourlier D., GoursatP. Colloque de l'AFC, 4-5 Février 1998, Orléans, France. Le projet SOLEIL. Morin P. Atelier MIMA98, 13 Mars 1998, Saclay, France. Multiionisation et explosion coulombienne moléculaire en champ laser intense. Hering Ph., Cornaggia С. 2nd International Workshop on Laboratory Astrophysics with Intense Lasers, 19-21 Mars 1998, University of Arizona, Tucson, Etats-Unis. Opacity study on iron in the 15-30 eV temperature range. Chenais-Popovics C, Merdji H., Missalla T., Gilleron F., Gauthier J.C., Blenski T., Perrot F., Klapish M., Bauche-Arnoult С, Bauche J., Eidmann К. 11th APS Topical Conference on Atomic Processes in Plasmas, 22-26 Mars 1998, Auburn, Etats-Unis. Effect of configuration interaction in M-shell samarium opacities. Merdji H., Blenski T., Missalla T., Chenais-Popovics C, Gauthier J.C.. Perrot F., Eidmann К. Journée de la section Atomes et Molécules du LURE, 25 Mars 1998, Orsay, France. Effets dynamiques et fragmentation sélective dans des molécules excitées en couche interne. Simon M., Miron C, Leclercq N., Guillemin R., Morin P. Journées femtoseconde du DRECAM, 27 Avril 1998, Saclay, France. Multiionisation moléculaire induite par laser. Hering Ph., Cornaggia С. 1er* Conférence Roumaine sur les Matériaux Carbonés, 25-26 mai 1998, Bucarest, Roumanie. Poudres à base de carbone contenant des fullerènes par interaction laser-Hydrocarbures. Alexandrescu R.. Armand X. Cauchetier M., Herlin N., Morjan I., Petcu S., Voicu I. European Conference on Laser Interaction with Matter-98, 4-8 Mai 1998, Formia, Italie. Experimental and theoretical studies ofL-shell iron opacities. Merdji H., Chenais-Popovics С, Missalla T., Gauthier J.C., Blenski T., Perrot F., Bar-Shalom A., Klapisch M., Bauche-Arnoult C, Bauche J., Eidmann K. Réunion du Groupe Français de Photochimie, 4-5 juin 1998, Paris, France. Relaxations intra - et inter-moléculaires en solution. Etude en spectroscopie de fluorescence femtoseconde. Gustavsson T.. Diraison M., Pommeret S., Mialocq J C. Effet d'un champ électrique local sur le transfert photoinduit d'électron Tran-Thi Т.Н.. Sharonov A.Yu., Hynes J.T. E-MRS Spring Meeting, 16-19 juin 1998, Strasbourg, France. Optical properties of nanocrystalline Silicon thin films produced by size-selected cluster beam deposition. Laguna M.A., Paillard V., Kohn В., Ehbrecht M., Huisken F., Ledoux G., Papoular R., Hofmeister H. 5e"1' colloque sur la Dynamique des Ions, des Atomes et des Molécules (DIAM), 7-10 Juillet 1998, Reims, France. Sélectivité et mouvement nucléaire dans la dynamique de relaxation de molécules excitées en couche interne. Miron С Simon M., Leclercq N., Morin P. 127 Ultrafast Phenomena 98, 12-17 Juillet 1998, Garmish-Partenkirchen, Allemagne. Kilohertz high harmonic generation in hallow core fibers. Garzella P.. Breger P., Agostini P., Constant E., Mevel E., Salin F., Dorrer C, Le Blanc C. 6th International Conference on X-Ray Lasers, 31 Aout-4 Septembre 1998, Kyoto, Japon. Investigation of population inversion from field ionized ions followed by double electron capture into nln'V- levels. Auguste T.. d'Oliveira P., Hulin S., Monot P., Faenov A.Ya., Pikuz T.A., Magunov A.I., Skobelev I.Yu., Rosmej F.B. Conduction and Transport Mechanisms in Organic Materials, 27-30 Septembre 1998, Heidelberg, Allemagne. Influence of disorder on electronic excited states: an experimental and numerical study of alkyithiotriphenylene columnar phases. Marguet S., Markovitsi D., Millie Ph., Sigal H., Kumar S. IXth International Conference on the Physics of Highly Charged Ions, 14-18 Septembre 1998, Bensheim, Allemagne. Radiation from autoionising levels correlated with single excited states of highly charged ions in dense cold plasmas. Rosmei F.B.. Faenov A.Ya., Pikuz T.A., Skobelev I.Yu., Flora F., Bollanti S., Di Lazzaro P., Letardi T., Vigli-Papadaki K, Notolla N., Grilli A., Palladino L., Reale A., Scafati A., Reale L., Auguste T., d'Oliveira P., Hulin S., Monot P., Zigler A., Fraenkel M. Colloque PCMI, 16-18 Septembre 1998, Toulouse, France. Structure de petits agregats silicium-carbone. Millie" Ph., Bertolus M. Analogues terrestres de poussieres carbonees interstellaires : hypotheses de depart et demarche experimental. Rouzaud J.N.. Galvez A., ClinardC, Herlin-Boime N., ReynaudC. 6eme Reunion des Chimistes Theoriciens Franc.ais, 13-16 Octobre 1998, Villeneuve d'Ascq, France. Methode de Car et Parrinello : mise en oeuvre dans le cas de petits agregats silicium-carbone. Bertolus M.. Finocchi F., Brenner V., Millie1 Ph. Transfert de charge dans les systemes ion-molecules : mise en evidence et modelisation. Hovau S., Brenner V., Dognon J P., Millie Ph. Simulation des melanges alcanes - molecules polaires : derivation de potentiels. Delhommelle J.. Granucci G., M11116 Ph., Boutin A., Fuchs A. Etude theorique preliminaire de la photoionisation acide du phenol et du cyanophenol. Granucci G.. Millie Ph., Hynes J.T., Than-Thi T.H. Workshop on European Synchrotron Light Sources, 5-6 Novembre 1998, Universite de Dortmund, Allemagne. Magnetic design and recent results on the OPHELIE undulator at Super ACO. Marcouilie P.. Corlier M., Brunelle P., Marteau F., Peaupardin P., Sommer M. et Nahon L. Status report of the Super-ACO FEL Roux R. Atelier Laser Megajoule et Astrophysique, 9-10 Novembre 1998, Observatoire de Paris, Meudon, France. Absorption des transitions 2-3 duferpar unefeuille chauffee par laser. Chenais-Popovics C. Merdji H., Missalla T., Gilleron F., Gauthier J.C., Blenski T., Klapish M., Bauche- Arnoult C, Bauche J., Eidmann K. llime Journees Nationales sur les Composites, 18-20 Novembre 1998, Arcachon, France. Effets d'ajouts d'aluminium ou de bore sur revolution thermique de poudres nanocomposites Si/C/N. ArmandX.. Herlin-Boime N., Mayne M.Cauchetier M. 128 3rd project meeting " Development of a Combined Synchrotron Radiation and VUV Free Electron Laser Facility ", 23 Novembre 1998, Daresbury, Royaume-Uni. Mirrors of the ELETTRA storage ring FEL project. Renault E. First network meeting " Towards a Storage Ring Free Electron Laser at 200 nm ", 1-2 Fe"vrier 1999, Orsay, France. The operation of the Super-AGO FEL source. Renault E. Transient absorption in the UV. Renault E. Survey on the international situation for FELs in the UV and european context. Couprie ME. Intense Laser Fields : X-Ray Generation and Applications, 8-12 Mars 1999, Les Houches, France. Ultrafast dynamics measurements of hot electrons in SiC>2 using high-order harmonic generation. Oue"r6F., Martin Ph., Petite G., Guizard S., Merdji H., Carre" B., Hergott J.F. VUV FEL User Workshop, 11-12 mars 1999, Hambourg, Allemagne. Time-resolved photoelectron spectroscopy with the TESLA-FEL on laser-produced photofragments. Nahon L. American Physical Society Centennial Meeting, 20-26 Mars 1999, Atlanta, Etats-Unis. Application of density functional theory and Car and Parrinello 's method to the study of small silicon- carbon clusters. Bertolus M., Millie" Ph., Finocchi F. Energy transfer and electronic coupling in columnar liquid crystals. Gallos L.K., Argyrakis P., Markovitsi D. PAC 99, 22-26 Mars 1999, New York, Etats-Unis. First results obtained with the electromagnetic crossed overlapped undulator OPHELIE at Super-ACO. Corlier M., Besson J.C., Brunelle P., Claverie J., Godefroy J.M., Herbeaux C, Lefebvre D., Marcouille" O., Marlats J.L., Marteau F., Michaut J., Peaupardin P., Petit A., Sommer M., Ve"t6ran J., Nahon L. 17th Advanced Beam Dynamics Workshop on Future Light Sources, APS, 5-17 Avril 1999, Argonne, Etats-Unis. The Super-ACO FEL. Couprie M. E. Ultimate characteristics ofSRFELs. Couprie M. E. Report of the "Ring Based-Sources" working group. Couprie M. E. Ultra-Intense Laser Interaction and Application I, 7-11 Mai 1999, Elounda, Grece. Ultrafast time resolved photoemission spectroscopy using high-order harmonics generation. Merdji H., Quere" F., Martin Ph., Petite G., Guizard S., Salieres P., Gobert O., Carre" B. E-MRS Spring Meeting, 31 Mai - 4 Juin 1999, Strasbourg, France. Photoluminescence of silicon nanocristallites : an astrophysical application. Ledoux G., Guillois O., Reynaud C, Huisken F., Kohn B., Paillard V. IV Journees des Phenomenes Ultra-rapides, 21-22 Juin 1999, Dijon, France. Etude experimental et theorique de Vaccord de phase des harmoniques d'ordre eleve generees dans des fibres creuses. Hergott J.F., Salieres P., Carre" B., Le De"roff L., Merdji H., Agostini P., Breger P., Garzella D., Constant E. Generation d'harmoniques d'ordre eleve: mesure de la coherence spatiale et temporelle. LeDeroffL.. Carre" B., Salieres P. 129 La spectroscopie de fluorescence résolue en temps par conversion de fréquence. Quelques exemples des études de réactivité en phase liquide. GustavssonT,, Mialocq J.C. Explosion coulombienne moléculaire induite par laser femtoseconde en polarisation linéaire et circulaire. Hering Ph., Cornaggia С, Brewczyk M. ECERS VI, 20-24 Juin 1999, Brighton, Royaume-Uni. Synthesis ofnanometric Si/C/N/B preceramic powders by laser spray pyrolysis. Armand X., Herlin-Boime N., Mayne M., Cauchetier M. Physique en Herbe 99, 20-25 Juin 1999, Ile d'Oléron, France. Reaction dynamics of barium on large van der Waals clusters. Briant M., Gaveau M.A., Mestdagh J.M., Visticot J.P. Applications of High Field and Short Wavelength Sources VIII, 26-30 Juin 1999, Potsdam, Allemagne. Frequency-domain interferometry in the XUVwith high-order harmonics. Salières P., Le Déroff L., Hergott J.F., Merdji H., Carré В., Auguste T., Monot P., d'Oliveira P. Photoprocesses in Molecular Assemblies, 27-30 Juin 1999, Dourdan, France. Electronic coupling responsible for energy transfer in columnar liquid crystals. Marguet S., Markovitsi D., Gallos L., Sigal H., Millie Ph., Argyrakis P., Ringsdorf H., Kumar S. 8th International Laser Physics Workshop (Lphys'99), 2-6 Juillet 1999, Budapest, Hongrie. Time resolved hot electrons relaxation measurements in SiO2. Martin Ph.. Quere F., Petite G., Guizard S., Merdji H., Carré В. Coherence properties and applications of high-order harmonics. Lynga С Bellini M., Delfín С, Descamps D., Gaarde M.B., Hansen T.W., Hergott J.F., L'Huillier A., Merdji H., Norin J., Salières P., Wahlström CG. Applications in Structural Biology, 4-8 juillet 1999, Hambourg, Allemagne. Perspective of the transient absorption spectroscopy : ionization of DNA components in aqueous solution. Renault E., Nahon L., Nutarelli D., Garzella D., Guillou T., Couprie M.E., Mérola F., Billardon M. XXXIst Europhysics Conference, European Group for Atomic Spectroscopy (EGAS), 6-9 Juillet 1999, Marseille, France. Emission line polarization degrees and nlm distributions produced by state-selective one-electron capture in slow Kr8* - Li(2s) collisions. Jacquet E., Kucal H., Pascale J., Bazin V., Boduch Ph., Lecler D., Chantepie M. SPIE International Symposium on Optical Sciences : accelerator-based sources of Infra-Red and spectroscopie applications II, 18-23 Juillet 1999, Denver, Etats-Unis. Two-color experiments combining the UV-storage ring free electron laser and the SA5IR beamline at Super- ACO. Nahon L.. Renault E., Couprie M.E., Nutarelli D., Garzella D., PolackF., Dumas P., Carr G.L., Williams G. Optical design and performances of the IR microscope beamline at super-ACO. PolackF., Nahon L., Mercier R., Armellin C, Marx J.P., Tanguy M., Delboubé A., Couprie M.E., Dumas P. Commissioning of OPHELIE : a variable polarization electromagnetic undulator for the SU5 VUV beamline at Super-ACO. Nahon L., Alcaraz Ch., Thissen R., Corlier M., Peaupardin Ph., Marteau F., Marcouillé O., Jolly A., Drecher M. 7th International Conference on Modelling, Monitoring and Management of Air Pollution, 27-29 Juillet 1999, Palo-Alto, Californie, Etats-Unis. Benzene and toluene chemical sensors. Towards a monocyclic aromatic hydrocarbon badge for individual exposure. Calvo-Munoz M.L., Tran-Thi Т.Н., Roux С. 130 FEL 99, 21-27 Août 1999, Hambourg, Allemagne. Super ACO FEL oscillation at 300 nm. GarzellaD., Nutarelli D., Renault E., Nahon L., Couprie M.E. Photobiology by the transient absorption of different FEL excited chromophoric compounds at Super-ACO storage ring FEL. Renault E. Is' Conference on Inertial Fusion Sciences and Applications (ISFA 99), 12-17 Septembre 1999, Bordeaux, France. Measurement of the absorption coefficients of Al and Ni thin foils at 15-25 eV temperatures. Chenais-Popovics С Fajardo M., Merdji H., Teubner U., Gauthier J.C., Renaudin P., Gary S., Bruneau 1, Perrot F., Blenski T., Andiel U., Fölsner W., Eidmann K. Charge exchange induced formation of hollow ions in high energy density plasmas. Rosmei F.B., Hoffmann D.H.H., Faenov A.Ya., Pikuz T.A., Magunov A.I., Skobelev I.Yu., Auguste T., d'Oliveira P., Hulin S., Monot P., Andreev N.E., Chegotov M.V., Veisman M.E. Réunion DFG-CNRS Elementary Chemical Processes in Liquids, 6-8 octobre 1999, Bad Herrenalb, Allemagne. Ultrafast relaxation processes of photoexcited triarylpyrylium cations. Gustavsson T., Markovitsi D., Gulbinas V. Journées femtoseconde du DRECAM, 14-15 Octobre 1999, Saclay, France. Multiionisation moléculaire : dynamique et explosion coulombienne. Hering Ph., Cornaggia C. Etats excités des fragments issus de l'explosion coulombienne moléculaire. Ouaglia L., Forest M., Cornaggia С Génération d'harmoniques dans une fibre creuse et focalisation par lentille de Bragg-Fresnel. Hergott J.F., Carré В., Merdji H., Salières P., Zeitoun P., Le Pape S., Garzella D., Breger P., Agostini P. Expériences d'interférométrie utilisant les harmoniques. Merdji H., Hergott J.F., Carré В., Salières P., d'Oliveira P., Monot P., Auguste T. Interaction laser-diélectriques : claquage optique et UPS résolue en temps. Ouéré F.. Guizard S., Martin P., Petite G., Merdji H., Hergott J.F., Le Déroff L., Carré B. Séparation de charges dans les agrégats moléculaires. Grégoire G., Dimicoli L, Mons M., Dedonder-Lardeux C, Jouvet C, Martrenchard-Barra S., Solgadi D. Intercorrélation et mesures des impulsions XUVpar élargissement pondéromoteur. Paul P.M., Breger P., Cheret M., Agostini P., Tana.E., Muller H.G. 7th Annual Workshop on European Synchrotron Light Sources, 7-9 Novembre 1999, Berlin, Allemagne. Super-ACO storage ring FEL and its applications. Renault E. Réunion du Groupe Français de Photochimie, 18-19 Novembre 1999, Paris, France. Couplage électronique et transfert d'énergie dans des cristaux liquides colonnaires. Markovitsi D., Mar guet S., Gallos L., Sigal H., Millié Ph., Argyrakis P., Ringsdorf H., Kumar S. Workshop on Relativistic Effects in Laser-Matter Interactions , 19-20 Novembre 1999, Saclay, France. 19 2 Electrons temperature studies of optical-field N2 plasma at 10 W/cm . Monot P. TMR Network Meeting, 22 Novembre 1999, Eindhoven, Hollande. The Super-ACO FEL group activity : Theory versus experiment. Couprie M. E. Transient absorption spectroscopy on FEL-excited samples : applications in biology (vis-UV) and in material sciences (IR). Nahon L. 131 15еше Congrès Français sur les Aérosols, 8-9 Décembre 1999, Paris, France. Utilisation et étude d'un générateur d'aérosols pour la synthèse de poudres céramiques nanométriques. Mayne M., Allain N., Armand X., Herlin-Boime N., Cauchetier M. Colloque Utilisateur du Lure : table ronde FELs et Applications, 9-10 décembre 1999, Orsay, France. From Super-ACO to SOLEIL : the SR-FELs applications side. Nahem L. Biomédical Applications of Free Electron Lasers, 23-28 Janvier 2000, San Jose, Etats-Unis. Transient absorption spectroscopy using the Super-ACO storage ring FEL. Renault E., Nahon L., Nutarelli D., Garzella D., Couprie M.E., Mérola F. 20th Workshop of Physics of High Energy Density in Matter, 31 Janvier-4 février 2000, ffirshegg, Autriche. Direct spectrocopic observation of multiple-charged MeV ions acceleration by intense femtosecond-pulse laser. Faenov A.Ya., Skobelev I.Yu., Magunov A.I., Pikuz T.A., Auguste T., d'Oliveira P., Hulin S., Monot P., Zhidkov A.G., Sasaki A., Tajima T. Réunion du Groupe Français de Photochimie, 27-28 Avril 2000, Cachan, France. Photophysique et photochimie sur de gros agrégats de van der Waals. Gaveau M.A. Spectroscopie de molécules d'intérêt biologique mises en phase vapeur par une nouvelle méthode associant désorption laser et détente supersonique. Piuzzi F. Photoluminescence du silicium nanocristallin: effets de taille et application astrophysique. Reynaud C, Ledoux G., Guillois O., Kohn В., HuiskenF. 30th Annual Anomalous Absorption Conference, 21-26 Mai 2000, Ocean City, Mariland, Etats-Unis. Direct spectroscopie observation of multicharged MeV ions in plasma heated by intense femtosecond laser radiation Faenov A.Ya., Skobelev I.Yu., Magunov A.I., Pikuz T.A., Auguste T., d'Oliveira P., Hulin S., Monot P. , Zhidkov A.G., Sasaki A., Tajima T. Réunion Réseau GAUS-XRP, 2 Juin 2000, Pise, Italie. High order harmonie generation: Spectral selection and focusing - absolute photon number measurements. Hergott J.F., Salières P., Merdji H., Carré В., Zeitoun Ph., Le Pape S., Agostini P. The IEEE International Conference on Plasma Science, 4-7 Juin 2000, New Orleans, Louisiane, Etats- Unis. X-ray spectromicroscopy investigation of fast ions and hot electrons in plasmas, heated by nanosecond laser radiation with different wavelengths. Faenov A.Ya., Skobelev I.Yu., Magunov A.I., Pikuz T.A., Rosmej F.B., Hoffmann D.H.H., Suss W., Geissel M., Bock R., Letardi T., Flora F., Bollanti S., Di Lazzaro P., Satov Yu.A., Smakovskii Yu.B., Stepanov A.E., Roerich V.K., Khomenko S.V., Nischuk S., Makarov K.N., Reale A., Scafati A., Auguste T., d'Oliveira P., Hulin S., Monot P., Sharkov B.Yu. ISSI Workshop on the Role of Laboratory Experiments in the Characterisation of Cosmic Materials, 8-12 Mai 2000, Berne, Suisse. Synthesis and properties of carbon materials of astrophysical interest. Reynaud C. Progress and open questions in the problem of the identification of the Unidentified Infrared (UIR) bands carriers in the frame of the solid state hypothesis. Guillois O. 132 Organic-Inorganic Hybrids : Science, Technology and Applications, 12-14 juin 2000, Guilford, Royaume-Uni. Monocyclic aromatic hydrocarbon sensors based on sol-gel material Calvo-Mufloz M.L., Tran-Thi T.H., Roux C, Bourgoin J.P., Ayral A., El-Mansoun A. 7th International Conference on X-Ray Lasers, 19-23 Juin 2000, Saint-Malo, France. Measurement of the wavefront of several XUV sources. Le Pape S., Zeitoun Ph., Hergott J.F., Carre" B., Dhez P., Francois M., Idir M., Merdji H., Ros D., Carillon A., SalieresP. Recombination X-Ray laser scheme in an optically ionized plasma, HulinS., Jacquemot S., Bonnet L., Lefebvre E., Auguste T., Monot P., d'Oliveira P. 133 PhD Theses Bertolus Marjorie Etude de petits agrégats mixtes par la méthode de la fonctionnelle de la densité et par des potentiels modèles. Thèse de l'Université Paris XI, Orsay, le 5 Octobre 1998. Dobosz Sandrine Interaction d'agrégats de gaz rares avec un champ laser intense. Thèse de l'Université Paris XIII, Villetaneuse, le 30 Novembre 1998. Sublemontier Olivier Mise au point d'un dispositif expérimental pour l'étude collisionnelle de complexes ioniques. Mémoire de diplôme d'ingénieur CNAM, le 11 Décembre 1998. Roux Raphaël Dynamique et conditions de stabilité du laser à électrons libres de Super-ACO. Fonctionnement avec une cavité RF simple ou double. Thèse de l'Université Paris VI, le 28 Janvier 1999. Grégoire Gilles Séparation de charges dans les agrégats moléculaires : Dynamique et spectroscopie. Application au système Nal -(solvants polaires)„. Thèse de l'Université Paris XI, Orsay, le 3 Février 1999. Gisselbrecht Mathieu Spectroscopie induite par laser sur des espèces atomiques et moléculaires préparées par un rayonnement VUV. Thèse de l'Université Paris XI, Orsay, le 25 Juin 1999. Ledoux Gilles Etude de la photoluminescence du silicium nanocristallin : application astrophysique à l'Emission Rouge Etendue. Thèse de l'Université Lyon I, le 14 Octobre 1999. Galvez Aymeric Elaboration, organisation et propriétés de nanoparticules de carbone modèles de la poussière interstellaire. Thèse de l'Université d'Orléans, le 22 Octobre 1999. Petcu Stela Réactions chimiques hétérogènes induites par pyrolyse laser : applications à la synthèse de poudres carbonées et defullerènes. Thèse de l'Université de Bucarest, le 2 Novembre 1999. Féret Laurent Etude théorique d'un atome ou ion à deux électrons actifs par une méthode d'interaction effective. Thèse de l'Université Paul Sabatier, Toulouse, le 5 Novembre 1999. Le Déroff Laurent Etude des propriétés de cohérence de la génération d'harmoniques d'ordre élevé : qualité du faisceau, cohérence spatiale et temporelle et application. Thèse de l'Université Paris VI, le 29 Novembre 1999. 135 Hering Philippe Contribution a I'etude de la multiionisation et de la fragmentation moleculaire en champ laser intense. These de 1'University Paris XIII, Villetaneuse, le 9 Decembre 1999. Marquette Arnaud Etude de la relaxation radiative (UV-visible) d'atomes et de petites molecules excites en couche interne par rayonnement synchrotron. These de 1'University de Lille, le 17 Janvier 2000. Nutarelli Daniele Dynamique et performance du laser a electrons libres de Super-ACO avec une cavite RF harmonique a '500 MHz. These de 1'University Paris XI, Orsay, le 20 Janvier 2000. Bondkowski Jens Cristaux liquides colonnaires du triphenyiene : etude spectroscopique des etats triplets et des porteurs de charge. These de l'Universitd Paris XI, Orsay, le 2 Mars 2000. 136 Popularization articles Agostini P. Atome habille par un champ laser intense. Clefs CEA, numero spécial sur les interactions photons-matière, 41, 4 (1999). Bonnaud G., Lefebvre E., Monot P. Effets relativistes dans l'interaction laser-plasma à ultra-haute intensité^ Clefs CEA, numéro spécial sur les interactions photons-matière, 41, 39 (1999). Bonnet L., Jacquemot S., Miquel J.L., Auguste T. Physique atomique hors équilibre et laser X. Clefs CEA, numéro spécial sur les interactions photons-matière, 41, 26 (1999). Cauchetier M., Mayne M., Goursat P., Besson J.L. La photochimie infrarouge au service des matériaux céramiques. Clefs CEA, 42, 22 (1999). Cornaggia C, Simon M., Morin P., Nenner I. Explosion moléculaire induite par laser et rayonnement synchrotron. Clefs CEA, numéro spécial sur les interactions photons-matière, 41, 66 (1999). Couprie M.E. Le rayonnement synchrotron, pour quoi faire ? Le rayonnement synchrotron, outil de recherche polyvalent Encyclopédie Larousse Bordas (2000) Gaveau M.A. Voyage au centre de l'agrégat. Phases magazine, 25 (2000). Guillois O., Ledoux G., Reynaud С Des nanocristaux de silicium dans l'espace. Phases magazine, 23 (2000) Markovitsi D., Marguet S., Millié Ph. Cristaux liquides colonnaires : Systèmes modèles pour une description quantitative de la migration d'excitation. Sciences chimiques, Lettres des départements scientifiques du CNRS, 71,4 (1999). Markovitsi D., Lavery R. Réflexions sur la chimie physique. Actualité Chimique, 11-12, 26, (1998). Markovitsi D., Mordenti L, Lorsque les molécules jouent avec un ballon de lumière. CNRS Info, 379, 19, (1999). Mons M., Grégoire G., Jouvet С Impulsions courtes et dynamique réactionnelle. Clefs CEA, numéro spécial sur les interactions photons-matière, 41,56 (1999). Salières P., Carré B. Des harmoniques plus vives que l'éclair. Phases magazine, 21 (1999). 137 Salieres P., Carre" B. L'arc-en-ciel des harmoniques d'un laser intense. Clefs CEA, numero special sur les interactions photons-matiere, 41,19 (1999). Salieres P., Lewenstein M. Table-top lasers crash through the water window. Physics World, 11, 26, (1998). Salieres P. L'arc-en-ciel des harmoniques d'un laser intense. Dejeuner de Presse DSM en l'honneur de C. Cohen-Tannoudji, Paris, 17 Novembre 1999. Salieres P. L'arc-en-ciel des harmoniques d'un laser intense. Dejeuner de Presse DSM en l'honneur de C. Cohen-Tannoudji, Paris, 17 Novembre 1999. Schmidt M Systemes moleculaires en champ laser intense et bref Dejeuner de Presse DSM en l'honneur de C. Cohen-Tannoudji, Paris, 17 Novembre 1999. Schmidt M., Normand D. Systemes moleculaires en champ laser intense et bref. Clefs CEA, nume"ro special sur les interactions photons-matiere, 41, 61 (1999). Villain P., Lewenstein M. Vers un nouvel etat de la matiere: Le condensat de Bose-Einstein. Clefs CEA, numdro special sur les interactions photons-mati&re, 41, 51 (1999). PATENT Brevet No. 99.12949. Procede pour la generation de lumiere dans I 'extreme UV pour la microlithographic Schmidt M. et Sublemontier O. (1999) 138 SPAM WITHIN THE SCIENTIFIC COMMUNITY Scientific awards 141 Networks and contracts 143 Relations with Universities • Corresponding Research Laboratories 147 • Teaching 149 • Reception of University students and other scholars 151 Collaborations with other laboratories 153 Post-docs 155 Foreign visitors 156 Organisation of conferences and workshops 157 Evaluation of research • Evaluation of laboratories, program committees and evaluation committees 159 • Thesis committees 161 • Young scientist seminars 165 139 Scientific awards M.E. Couprie 1998 : Prix de 1'Interdivision "Acce"16rateurs et Techniques Associe'es" de la Societe" Franc, aise de Physique. M. Schmidt 1998 : Prix "Aime" Cotton" de la Socie"t6 Francaise de Physique. 141 Networks and Contracts Groupements de Recherche Groupe Poudres Laser et Grains Interstellaires GDR CNRS n°1168 "Etude physico-chimique de poudres ceramiques nanophasiques a base de silicium" (1998-2000) Groupe Poudres Laser et Grains Interstellaires GDR CNRS n°1752 "Nanotubes" (1999-pr6sent) Groupe Photophysique Photochimie en phase condensfe GDR CNRS n° 1017 "Processus elementaires en phase liquide" (1997-2000) Groupes Photophysique Photochimie en phase gazeuse et Chimie The"orique GDR CNRS-CEAn°1021 "Agregats" (1998-1999) Groupes Photophysique Photochimie en phase gazeuse - Chimie Th6orique - Applications des Plasmas GDR CNRS-CEA n°2107 "Agregats etReactivite" (2000-pr&sent) Groupes Interaction Laser Matiere en Champ Fort - Applications des Plasmas - G6n6ration d'harmoniques GDR SAXO n°1851 "Nouvelles Sources de Rayons X et leurs Applications" (1999-pr6sent) National Programs Groupes Poudres Laser et Grains Interstellaires et Chimie Th6orique Programme national CNRS-CEA-CNES "Physique et Chimie du Milieu Interstellaire" (1996-1999) Groupe Applications des Plasmas CEA-CNRS-Universit6-Industrie "Programme sur la lithographie dans Vextreme UV (PREUVE)" (1999-2001) European Networks Research Training Networks Rayonnement Synchrotron M.E. Couprie (coordonnateur) "Towards a storage ring free electron laser source at 200 nm" (1997-2001) Rayonnement Synchrotron M.E. Couprie "Development of a combined Synchrotron Radiation and VUVfree electron laser facility" Poudres Laser et Grains Interstellaires N. Herlin Nanomat: "Nanopowders : preparation and processing NANOMAT" (1998-2002) Interaction Laser Matiere en Champ Fort P. Agostini: "Generation and applications of ultra-short X-ray pulses" (1996-2000) 143 Interaction Laser Matiere en Champ Fort P. Salieres : "Generation and characterization of attosecond pulses in strong laser-atom interaction" (2000 - 2004) Access to Research Infrastructure Rayonnement Synchrotron M.E. Couprie, rdseau en liaison avec le laboratoire ELETTRA, Trieste, Italie "Combined synchrotron radiation and VUVfree electron laser facility" Marie Curie Fellowships Chimie Thdorique Ph. Milli6 - G. Granucci (post-doc 06/1997 - 06/1999) "Photo-induced acid base chemistry in solution : excited state phenol reaction dynamics in water" Photophysique Photochimie en phase condensed T.H. Tran-Thi - M.L. Calvo-Munoz (doctorante 10/1997-09/2000) "Capteurs chimiques d'hydrocarbures aromatiques monocycliques" Applications des Plasmas M. Schmidt - Christoph Ellert (post-doc 10/1998-02/2000) "Agregats metalliques en champ laser intense et ultra-bref Program COST Photophysique Photochimie en phase condensed D. Markovitsi Programme COST D14 - (1999-2003) "Experimental and modelling aspects of electron and energy transfer in organised molecular materials" Rayonnement Synchrotron L. Nahon DESY COST RTD - 5thprogramme (2000-2003) "Development of a pump-probe facility with sub-picosecond time resolution combining a high-power optical laser and a soft X-ray free electron laser" Program INT AS Interaction Laser Matiere en Champ Fort C. Cornaggia "Experimental and theoretical study of molecular dynamics in a strong laser field" (May 2000 - April 2003) Interaction Laser Matiere en Champ Fort P. Agostini "Coherence and interference effects in high harmonic generation and above threshold ionization" (May 2000 - April 2003) 144 Joint Research Programs France-Allemagne : Programme "Procope", D. Markovitsi avec D. Haarer, Université de Bayreuth, Allemagne "Etude de transfert de charges dans des cristaux liquides colonnaires photoconducteurs" (1998-1999) France-Allemagne : Programme "Procope", С. Reynaud avec F. Huisken, Max Planck Institut, Götüngen, Allemagne "Propriétés optiques de films minces nanostructurés produits par dépôt de clusters" (1999-2000) France-Allemagne : Programme "Procope", N. Herlin avec F. Aldinger, Max Planck Institut, Stuttgart, Allemagne "Synthèse et comparaison de pré-céramiques amorphes Si/C/N obtenues par pyrolyse laser ou thermolyse en four" (2000 - 2002) France-Pologne : Programme "Polonium", T. Blenski avec K. Rzazewski, Institut de Physique de Г Académie Polonaise des Sciences "Approche hydrodynamique pour l'étude de la dynamique de liquides fermioniques et bosoniques" (1997-2000) France-Russie : Ministère des Affaires Etrangères T. Auguste avec A. Faenov et T. Pikuz, Mendeleiev National Institute of Physical-Technical and Radiotechnical Measurements, Moscou "Spectroscopie X des interactions laser-matière sous éclairement laser extrême" France-Roumanie : Ministère des Affaires Etrangères M. Cauchetier, С Reynaud avec Y. Voicu, Institut de Physique Atomique de Bucarest "Réactions chimiques hétérogènes induites par pyrolyse laser : application à la synthèse de poudres carbonées de fullerènes" France-Etats-Unis : "NSF-CNRS", Т.Н. Tran-Thi avec J.T. Hynes, Université du Colorado, Boulder, Etats-Unis "Transfertphotoinduit de proton : expérience et théorie" (1997-2000) France- Etats-Unis : Contrat OTAN CRG (1992-présent) P. Agostini avec Di Mauro, Brookhaven National Laboratory, Upton New York, Etats-Unis "Electron correlation in multiphoton ionization" Other Research Contracts Chimie Théorique - Ph. Millié Avec la Direction du Cycle du Combustible (DCC/DPE) (1998-2000) "Etude théorique des colorants laser" Chime Théorique - Ph. Millié Avec le Haut Commissariat à l'Energie Atomique (1999-2001) "Interaction ion métallique-molécule : une action conjointe théorie-expérience" Chimie Théorique - Ph. Millié Avec Г Institut de Chimie des Substances Naturelles (CNRS) (1999) "Réactivité et énantiomères" 145 Interaction Laser Matiere en Champ Fort - T. Auguste Avec la Direction des Applications Militaires (DAM) (1997-2000) "Design and applications of laser-plasma X-ray lasers" Interaction Laser Matiere en Champ Fort - B. Carre", O. Gobert, J. Pascale, M. Poirier Avec la Direction du Cycle du Combustible (DCC/DPE) (2000) "Peuplement de niveaux metastables de Vion U* dans le procede SILVA" Matiere a Haute Densit6 d'Energie - T. Blensici Avec la Direction des Applications Militaires (DAM) (1997- 1999) "Calcul de laphotoabsorption dans lesplasmas denses" Serveurs Lasers - O. Gobert Avec la Direction du Cycle du Combustible (DCC/DPE) (2000) "Prise en compte des effets d'indice d'une vapeur epaisse sur la propagation" 146 Relationship with Universities Corresponding Research Laboratories In order to give a formal basis of the relations between CEA and University, the concerned ministerial offices for CEA has encouraged us to establish so-called LRC contracts. These contracts have a minimum duration of 2 years and are designed to link a CEA research group with a University laboratory thereby including a financial support for the University and University staff working at CEA. Team Polyatomic molecules and clusters in strong field Corresponding Research Laboratory (LRC) of the CEA, contract n° DSM 97-01 The research team of Professor Jean-Pierre Rozet, as a part of the Solid state physics group (GPS - University PARIS VI and PARIS VII) headed by Professor Jean Klein, works since many years in the field of fast, multiply charged ion impact physics and is a LRC laboratory of the CEA (contract n° DSM 97-01). The scientific activity is devoted to the study of high density of excitation in matter either induced by fast ion projectiles or by strong laser pulses : experiment and theory. Created in 1997 and renewed in 1999 for 2 years. Teams Polyatomic molecules and clusters in strong field and Photophysics and Photochemistry in the Gaseous Phase Corresponding Research Laboratory (LRC) of the CEA, contract n° DSM 97-02 The group « simple systems in strong laser fields » headed by Profs. Annick Suzor-Weiner and Alfred Maquet of the Laboratory of Chemical Physics Matter and Radiation (CPMR) at the University Paris VI - is a LRC laboratory of the CEA (contract n° DSM 97-02). The research project is divided into two main topics dealing with the interaction dynamics of molecules irradiated by ultra-short (lOfs a 1 ps) and intense laser pulses: Analysis and elucidation of the mechanisms responsible for molecular alignment Dynamic control of the molecular ionization and dissociation Created in 1997 and renewed in 1999 for 2 years. Team Production of coherent XUV light by harmonic generation and Applications Corresponding Research Laboratory (LRC) of the CEA, contract n° DSM 97-04 The research team «Intense lasers and Application » headed by Dr. Francois Salin, in collaboration with the group of Dr. Robert Gayet of the Center of Theoretical Physics and Modeling, at the University Bordeaux I is a LRC laboratory of the CEA (contract n° DSM 97-04, director Prof. Christian Stenz). The research project is focused on the study of the high order harmonic generation (HHG) in gases and includes two main activities: Theoretical study of relativistic effects in atomic and molecular physics induced by ultra-short and intense laser fields Development and applications of HHG sources at high repetition rate. Created in 1997 and renewed with the. collaboration of CEA/DAM. Team Polyatomic molecules and clusters in strong field Corresponding Research Laboratory (LRC) of the CEA, contract n° DSM 98-16 The laboratory of Chemical Physics Matter and Radiation (CPMR) at the University Paris VI, headed by Professor Alfred Maquet is a LRC laboratory of the CEA (contract n° DSM. 98-16). The research project in centered on two subjects: High order harmonic generation, especially with clusters. Laser-matter interaction in strong laser field. Created in 1999 for 4 years. 147 Team Interstellar Dust and Laser-produced Powders Corresponding Research Laboratory (LRC) of the CEA, contract n° DSM 97-03 The group "Novel ceramic materials" headed by Professor Goursat of the University of Limoges and of the Ecole Nationale SupeYieure de Ceramique Industrielle is a LRC laboratory of the CEA (contract n° DSM 97- 03). The research project is devoted to: Shaping and densification by sintering under high pressure of the laser-produced powders which have been synthesized at SPAM The study of thermo-mechanical properties of the developed materials Created in 1997 for 4 years. Teams Polyatomic molecules and clusters in strong field and Interstellar Dust and Laser- produced Powders Corresponding Research Laboratory (LRC) of the CEA, contract n° DSM 99-21 The "Laboratoire de Spectroscopie Ionique et Moleculaire" (LASIM) of University Claude Bernard (Lyon, UMR 5579) headed by Professor Michel Broyer is a LRC laboratory of the CEA (contract n° DSM 99-21) The research project is devoted to: Synthesis by laser Pyrolysis of carbon/silicon heterofullerenes Optical properties of large carbon clusters Heating of metal clusters with short and intense laser pulses Created in 2000 for 4 years. 148 Teaching University and continuing education Brenner V. "Préceptorat de Chimie des Liaisons" 2ième année, Ecole Supérieure de Physique et de Chimie Industrielles - ESPCI - Paris (1998-présent) lOh/an "Travauxpratiques de Chimie Quantique" Tronc commun du DEA de physico-chimie moléculaire, Université Paris XI - (1998-présent) - 16h/an Dimicoli I. "Cours Applications des lasers en analyse" DESS "Instrumentation et méthodes physico - chimiques d'analyse", Université Paris XI et INSTN (1998-présent) - 6h/an Fourni er P.R. "Cours Vide, cryogénie, bouteilles de gaz, gaz comprimés". Stage des animateurs de sécurité, INSTN, Saclay (1999-2000) - 8h/an Gilard F. "Ecole de spectrométrie de masse" Formation permanente CNRS - Université Paris XI - (2000) - 20h/an Granucci G. "Travaux dirigés de thermodynamique" Classes préparatoires PCEM - Université Paris XI - (1998) - 30h/an "Interrogations orales de thermodynamique et atomistique" DEUG Sciences de la vie, Université Paris XI (1998-1999) - 18h/an "Préceptorat de Chimie des Liaisons" 2ième année, Ecole Supérieure de Physique et de Chimie Industrielles - ESPCI - Paris (1999) - 10h/an Grégoire G. "Travauxpratiques lasers" DESS "Instrumentation et méthodes physico - chimiques d'analyse", Université Paris XI et INSTN (1998-2000) - 36h/an "Travauxpratiques d'optique" NFI Université Paris XI (1998-2000) - 60h/an Mayne M. "Travauxpratiques de chimie générale" DEUG Physique et Chimie, Université d'Evry - (1999) - 30h/an Mestdagh J.M. "Cours de Collision" Tronc commun du DEA de physico-chimie moléculaire, Université Paris XI (1998-2000) - 30h/an Millié Ph. "Cours et travaux dirigés en Chimie Quantique" Tronc commun du DEA de physico-chimie moléculaire, Université Paris XI (1998-présent) - 30h/an "Les méthodes de la fonctionnelle de la densité en chimie" 6ème Ecole d'été de Physico-Chimie Théorique, Marly-Le-Roi (6-10 septembre 1999) - 2h "Forces intermoléculaires et simulation numérique" Option du DEA de physico-chimie moléculaire, Université Paris XI (1998-présent) - 9h/an 149 Monot P. " Cours Optique et détection " DEA de Modélisation et Instrumentation en Physique - Université Paris VI (1999-présent) - 10h/an Morin P. "Applications du rayonnement synchrotron: photoionisation-photodissociation" D.E.A. - Université Paris VI (1998-présent) - 9h/an Nutarelli D. "Cours Physique du XXeme siècle" DEUG de Physique 2lème année, Université de Cergy-Pontoise (1997-1998) - 20h/an Poisson L. "Elaboration et encadrement de travaux pratiques de chimie organique" Monitorat à l'Ecole Polytechnique, Palaiseau (1998-2000) - 96h/an. "Encadrement de travaux pratiques de chimie organique" ENSTA, Palaiseau (1998-1999) - 12h/an Piuzzi F. "Cours Applications des lasers en analyse" "Organisation des travaux pratiques laser et des stages en entreprise des étudiants" DESS "Instrumentation et méthodes physico-chimiques d'analyse", Université Paris XI et INSTN (1998- présent) - 30h/an "Cours Applications physico-chimiques des lasers" DEA de Modélisation et Instrumentation en Physique, Université Paris VI (1998- présent) - 6h/an Simon M. "Cours Photoionisation et photodissociation en phase gazeuse dans le domaine UV-X mous" Option du DEA de physico-chimie moléculaire, Université Paris XI et du DEA de Chimie Inorganique Université Paris VI. (1998-présent) - 8h/an Tardivel B. "Travauxpratiques lasers" DESS "Instrumentation et méthodes physico-chimiques d'analyse", Université Paris XI et INSTN (1998-présent; - 12h/an. Thomas A.-L. "Travaux dirigés de thermodynamique et atomistique" Classes préparatoires PCEM Université Paris XI (1999-présent) - 44h/an "Préceptorat de Chimie des Liaisons" 2ième année, Ecole Supérieure de Physique et de Chimie Industrielles - ESPCI - Paris (1999-présent) 10h/an "Préceptorat de Réactivité" 3ième année, Ecole Supérieure de Physique et de Chimie Industrielles - ESPCI - Paris (1999-présent) 5h/an "Interrogations orales de Chimie" Classes préparatoires PCSI Lycée Biaise Pascal, Orsay (1999) - 20 h/an Visticot J.P. "Cours Spectroscopie en temps réel" Option du DEA de physico-chimie moléculaire, Université Paris XI (1998-2000) - 10h/an. 150 Reception of University students and other scholars Stagiaires 3eme Cycle Amaas D. Ecole Centrale de Lyon 4 mois et demi Becu L. Universit6 Paris VI 6 mois et demi Bouchon M. ESPEO 6 mois Bregeion T. University Paris XI 6 mois Bouvier B. University Paris XI 5 mois et demi Carre V. University de Metz 4 mois Dubois E. University de Marnes la Vall6e 4 mois Hergott J. F. University Paris XI 4 mois Lafon R. Broohaven National Laboratory 1 mois et demi Le Guen K. Universal Paris VI 5 mois Paul P. M. University Paris VI 4 mois Poisson L. Universit6 Paris VI 11 mois Quaglia L. Ecole Polytechnique et University Paris XI 2 mois Tessier E. University Paris VI 5 mois et demi Stagiaires 2eme Cycle Agnus G. Stage universitaire Licence 1 mois et demi Allain N. Stage universitaire Maitrise 5 mois Biasi A. Stage universitaire NFI 3 mois Brianne C. Stage universitaire Licence 1 mois et demi Campo D. Stage de Magistere 2 mois Dubin F. Ecole d'ing^nieur 4eme anne"e 3 mois Evain B. Stage universitaire Maitrise 1 mois et demi Guilloun C. Stage de Magistere 2 mois Mairesse Y. Stage universitaire Licence 1 mois etdemi Mairesse Y. Stage de Magistere 3 mois et demi Moneron G. Stage de Magistere 2 mois Moreau A. Stage Universitaire Maitrise 2 mois etdemi Moreau P. Stage universitaire Licence 1 mois etdemi Sacquin S. Stage de Magistere 1 mois et demi Teahu A. Stage Universitaire Maitrise 2 mois etdemi Stagiaires ler Cycle Dufrenoy Ph. Stage universitaire BTS 2 mois et demi Forterre M. Stage de fin d'&ude BTS 3 mois Gastori S. Stage E.N.C.P.B. 4 mois et demi Gerbron S. Stage universitaire IUT 3 mois Giordana C. Stage universitaire IUT 3 mois Lancry S. Stage universitaire IUT 3 mois Meski Nacer M. Stage universitaire IUT 3 mois Riedel D. Stage universitaire IUT 11 mois Rogombe M. Stage universitaire DUT 2 mois Roux J. Stage universitaire BTS 3 mois Vilmay M. Stage universitaire DUT 5 mois Zelmai: Y. Stage universitaire BTS 4 mois et demi 151 Collaborations with other laboratories without formal contract National Centre de Recherche sur la Matiere Divise"e, CNRS, Orleans. Centre d'Erudes des Lasers Intenses et Applications, CNRS, Bordeaux. Centre Interdisciplinaire de Recherche avec les Ions Lasers, L.S.A., University de Caen. Direction des Applications Militaires, CEA, Bruyeres le Chatel. Direction des Techniques Avanc6es, LETI, CEA, Saclay. Direction du Cycle du Combustible, DRRV, CEA, Marcoule. Direction du Cycle du Combustible, DPE, CEA, Saclay. Ecole Nationale Sup6rieure des Techniques Avanc6es, UMR 7639, Ecole Polytechnique, Palaiseau. Ecole Normale SupeYieure UMR 8640, Paris. Institut de Chimie des Substances Naturelles, CNRS, Gif sur Yvette. Institut d'Optique The'orique et Appliquee, CNRS, Orsay. Laboratoire Aim6 Cotton, CNRS, Orsay. Laboratoire de Chimie Physique, University Paris XI. Laboratoire de Chimie The'orique, University Paris VI. Laboratoire des Mat6riaux et Proce'des Membranaires , Ecole Nationale Sup&ieure de Chimie, Montpellier Laboratoire d'Optique Appliquee - des Techniques Avance'es, Palaiseau. Laboratoire de Photophysique Mole"culaire, CNRS, Orsay. Laboratoire de Physique des Solides, Universit6 Paris XI. Laboratoire de Physique Quantique, University de Toulouse. Laboratoire de Spectrom6trie Ionique et Moleculaire, University de Lyon. Laboratoire de Spectroscopie Atomique et Ionique, Universite" Paris XI. Laboratoire pour 1'Utilisation des Lasers Intenses, Ecole Polytechnique, Palaiseau. Service de Recherche sur les Surfaces et l'lrradiation de la Matiere, DRECAM, CEA, Saclay. Service des Ions, Atomes et Agre"gats, DRFMC, CEA, Grenoble. International Advanced Photon Research Center, JAERI, Japan. AMOLF FOM Institute for Atomic and Molecular Physics, Amsterdam, The Netherlands. Brookhaven National Laboratory, Upton New York, USA. Center for Theoretical Physics of the Polish Academy of Sciences, Warsaw, Poland. Hannover Universitat, Hannover, Germany. Institut fur Kernphysik, TU-Darmstadt, Darmstadt, Germany. 153 Institut fur Rontgenphysik, Universita't Gottingen, Gottingen, Germany. Institute for Molecular Sciences, UVSOR, Okasaki, Japan. Institute of Physics, Polish Academy of Sciences, Warsaw, Poland. Institute of Theoretical Physics, Warsaw University, Warsaw, Poland. Kuchatov Institute, Moscow, Russia. Laboratoire de Physique Atomique et Moleculaire, University Laval, Canada. Las Vegas University Nevada and Advanced Light Source, Berkeley, USA. Lund Institute of Technology, Lund, Sweden. Max Plank-Institute fur Quantenoptik, Garching, Germany. Max Plank-Institute fur Stromungsforschung, Gottingen, Germany. Multicharged Ions Spectra Data Center of VNIIFTRI, Mendeleevo, Moscow, Russia. Oregon University, Oregon, USA. Photon Factory, Tsukuba, Japan. Research Institute for Scientific Measurements, Sandai, Japan. Rheinliche Westphalische Technische Hochschule, Aachen, Germany. University libre de Berlin, Berlin, Germany. University Libre de Louvain La Neuve, Belgium. University Technique d'Aix la Chapelle, Aix la Chapelle, Germany. University of Bialystok, Bialystok, Poland. University of Missouri-Rolla, Rolla, Missouri, USA. Upsala University, Upsala, Sweden. Uzhgorod University, Uzhgorod, Ukraine. 154 Post-Docs Name Funding Dates Ceccoiti Tiberio. PREUVE contract 03.2000 au 02.2001 Ishikawa Kenichi CEA 10.1998 au 09.2000 De Niiino Giovanni CEA 10.1999 au 10.2000 Ellert Christoph EEC/Marie Curie Fellowship 09.1998 au 02.2000 Guard Françoise Contract 05.2000 au 12.2000 Granucci Giovanni EEC/Marie Curie Fellowship 06.1997 au 06.1999 Hoyau Sophie CEA 02.1998 au 08.1998 Merdji Hamed CEA 10.1998 au 09.2000 Mocellin Alexandra CNPq 01.2000 au 01.2001 Zao Qingchun EGIDE 11.1998 aulO. 1999 Renault Eric CEA 07.1998 au 06.2000 Rusek Marian CEA 07.1998 au 07.2000 Ténégal François CEA 09.1999 au 08.2000 155 Foreign Visitors Name Affiliation Date Alexandrescu Rodica Inst. of Physics and Technology of Radiation Devices, Bucarest, Roumania 1 month in 1998 Brewczyk Miroslaw University Bialystok and Center for Theoretical Physics, Warsaw, Poland 2 months over 1998-1999 Faenov Anatoli MISDC of VNHFTRI, Mendeleevo, Russia 2 months in 1998 Faubel Manfred MPI für Strömungsforschung, Göttingen, Germany 3 months over 1998-1999 P:ormichev Serguei Inst. Kourchatov, Moscow, Russia 2 months in 1999 Di Mauro Luigi Brookhaven National Laboratory, USA 3 months over 1998-1999 Ito Kenji Inst. of Materials structure Science, Tsukuba, Japon 2 months over 1998-1999 Mostowski Jan Inst. Of Physics, Warsaw, Poland 1 month in 1999 Müller Anita Max Planck Institute, Stuttgart, Germany 1 month in 2000 Pikuz Tatiana MISDC of VNIIFTRI, Mendeleevo, Russia 4 months over 1999-2000 Shigemasa Eiji National Laboratory for High Energy Physica KEK Japan 18 months over 1998-1999 Skobelev Igor MISDC of VNIJPTRI, Mendeleevo, Russia 2 months in 1998 Suran Vasyl Uzhgorod University, Uzhgorod, Ukraine 3 months in 1999 Voicu Ion Inst. of Physics and Technology of Radiation Devices, Bucarest, Roumania 1 month in 1999 Wieland Marek Inst. für Röntgenphysik, Göttingen, Germany 2 months in 1999 Zaretski David Inst. Kourchatov, Moscow, Russia 3 months over 1998-1999 156 Organization of conferences and workshop Agostini P. Co-Pr&ident du Workshop "Relativistic Effects in Laser-Matter Interaction", l'Orme des Merisiers, France, 19-20 Novembre 1999. Membre du comit6 de programme de Pisa 2000 "Atoms, Molecules and Quantum dots in laser fields: Fundamental processes", Pise, Italie, 12-16 Juin 2000. d'Oliveira P. Membre du comit6 d'organisation "Developpement et Applications des Sources X et UVX Intenses et Breves", Orsay, France, 5-6 Mars 1998. Dimicoli I. Membre du comit6 d'organisation "Energetique et reactivite des ions en phase gazeuse: experience et theorie", Gif sur Yvette, France, 15-17 Novembre 1999. Gustavsson T. Membre du comit6 d'organisation "Photoprocesses in molecular assemblies", Dourdan, France, 27-30 Juin 1999. Markovitsi D. Pr6sidente du comit6 d'organisation "Photoprocesses in molecular assemblies", Dourdan, France, 27-30 Juin 1999. Merdji H. Membre du comite" d'organisation "JECAM, Journies de conferences interdisciplinaires du DRECAM", Saclay, France, 17-19 Janvier 2000. Membre du comit6 d'organisation "Doctoriales Paris VI - Ecole Polytechnique", La Brosse-Montceaux, France, 15-21 Novembre 1998. Meynadier P. Membre du comit6 d'organisation "JECAM, Journees de conferences interdisciplinaires du DRECAM", Saclay, France, 17-19 Janvier 2000. Millie; Ph. Membre du comite" d'organisation "Photoprocesses in molecular assemblies", Dourdan, France, 27-30 Juin 1999. Morin P. Membre du comite' d'organisation du Workshop "Industrie et Recherche appliquee autour du Rayonnement Synchrotron", Aix en Provence, France, 28-29 Avril 1998. Reynaud C. Membre du comite" d'organisation du Workshop "The role of laboratory experiments in the characterisation of cosmic materials", Berne, Suisse, 8-12 Mai 2000 Simon M. Membre du comite' d'organisation de l'6cole the"matique "Detection, Temps, Position, Image", Universit6 Paris XI, Orsay, France, 3-5 Novembre 1999. 157 Evaluation of research Evaluation of laboratories, program committees, and evaluation committees Agostini P. Membre du comite de direction du Programme FEMTO de 1'European Science Foundation. Membre du comity de programme de LIF-ENSTA-X, Palaiseau. Coordinateur du projet INT AS "Coherence and interference effects in high harmonic generation". Carre B. Membre du comite de programme Atomes et Molecules du LURE (1998-present). Couprie M.E. Expert a Bruxelles : Bourse Marie Curie (5ieme PCRD) (1999). Reseau (5ieme PCRD) (1999). Gustavsson T. Membre de la commission de specialistes n° 8, Ecole Normale Superieure de Cachan (2000). Mestdagh J.M. Membre du groupe de travail dirigg par J. Dupont-Roc pour l'examen du Laboratoire d'Optique Quantique de Palaiseau (1999). Membre du conseil scientifique du Laboratoire de Photophysique Moleculaire (2000). President du comite de programme Atomes et Molecules du LURE (1998-present). President du comite devaluation du laboratoire de Chimie Quantique et Modeiisation (UMR7551) (2000). Membre du conseil de la Division de la Recherche de l'Universite Paris XI (1998-present). Membre du conseil scientifique de la Direction des Applications Militaires (1998-present). Membre du conseil scientifique du LURE (1999). Membre du conseil scientifique du GDR Agregats et Reactivite (2000-present). Membre du comite de suivi du Rayonnement Synchrotron (CEA-CNRS) (1999-present). Morin P. Membre du scientific and technical advisory comniitee of the Synchrotron Radiation Research Center of Taiwan (1998-2002). Membre de l'APD SOLEIL (Juillet 1996 Avril 1999). Participation et preparation des reunions du Conseil Scientifique SOLEIL. Normand D. Membre du conseil scientifique du Centre de Physique Theorique et de Modeiisation de Bordeaux. Reynaud C. Membre du conseil scientifique du Programme National CEA-CNRS-CNES "Physico-Chimie du Milieu Inters tellaire" (1996-present). Salieres P. Membre du comite scientifique du GDR SAXO (2000-present). Visticot J.P. Membre du comite scientifique de 1'Action Concertee Incitative "Photonique" (2000). 159 Thesis committees Agostini P. (Opponent at the PhD thesis defense) High order harmonics characterisation, optimisation and applications. Cl. Lynga - University de Lund, 19 Novembre 1999. Blenski Th. (rapporteur) Etude de la deformation du cortege electronique en presence d'un champ magnetique intense. P. Pourre - These de l'Universite' Paris XI, Orsay, 16 Septembre 1998. Blensld Th. (rapporteur) Etude du transfert radiatifet de I'opacite d'un plasma cree par rayonnement X. F. Gilleron - These de l'Ecole Polytechnique, 30 Juin 2000. Carr6 B. (rapporteur) Etats creux du lithium atomique et ionique. S. Diehl-Guilbaud - These de l'Universitg Paris XI, Orsay, 29 Mai 1998. Carre' B. (rapporteur) Extension du pompage des lasers X-UV aux ions nickelloi'des. Realisation d'un laser a 13.9 nm. Modelisation de la coherence spatiale des lasers X-UV. D. Ros - These de l'Universitd Paris XI, Orsay, 18 Decembre 1998. Carr6 B. (rapporteur) Spectroscopie laser sur des especes atomiques ou moleculaires preparees par un rayonnement VUV. M. Gisselbrecht - These de l'Universite' Paris XI, Orsay, 25 Juin 1999. Carre-B. Etudes des proprietes de coherence de la generation d'harmoniques d'ordre eleve: qualite du faisceau, coherence spatiale et temporelle et application. L. Le Deroff - These de l'Uni versit6 Paris VI, 29 Novembre 1999. M. Cauchetier Etude par RMN de poudres nanocomposites a base de silicium obtenues par pyrolyse laser de precurseurs organo-metalliques. Y. El Kortobi - These de l'Universit6 Paris VI, 2 Juin 1998 M. Cauchetier Etude spectroscopiques de nanomateriaux a base de carbure de silicim : structures et proprietes electroniques. S. Charpentier - These de l'UniversM du Maine, Le Mans, 25 Juin 1998 M. Cauchetier Couche minces nanostructurees de silicium et de carbure de silicium preparees par depot de petits agregats : structures et proprietes electroniques. P. Keghelian - These de l'Universit6 Claude Bernard, Lyon I, 12 Decembre 1998 Cauchetier M. Nanocomposites Sifl/SiC : stability thermique et densification des poudres SiCN (Al, 0) synthetisees par pyrolyse laser, comportement aufluage desfrittes. B. Doucey - These de l'Universite' de Limoges, 16 Decembre 1999. Cornaggia C. Contribution a V etude de la multiionisation et de la fragmentation moleculaire en champ laser intense. P. Hering - These de l'Universit6 Paris XIII, Villetaneuse, 9 Decembre 1999. 161 Couprie M. E. (rapporteur) Défauts locaux absorbants et diffusants, rôle et évolution dans l'irradiation. Corrélation et études multi- échelles. A. Gatto - Thèse de l'Université Saint-Jérôme, Marseille, 1er Octobre 1999. Couprie M. E. Dynamique et conditions de stabilité du laser à électrons libres de Super-ACO. Fonctionnement avec une cavité RF simple ou double. R. Roux - Thèse de l'Université Paris VI, 28 Janvier 1999. Couprie M. E. Dynamique et performances du laser à électrons libres de Super-ACO avec une cavité RF à 500 MHz, D. Nutarelli - Thèse de l'Université Paris XI, Orsay, 20 Janvier 2000. Dimicoli I. Séparation de charges dans les agrégats moléculaires. Dynamique et spectroscopie. Application au système Nal -(solvants polaires)„. G. Grégoire - Thèse de l'Université Paris XI, Orsay, 3 Février 1999. Gustavsson T. Caractérisation de billes de latex fluorescentes pour l'élaboration de nano-capteurs. R. Méallet-Renault - Thèse de l'Ecole Normale Supérieure de Cachan, 20 mars 2000. Herlin-Boime N. Elaboration, organisation et propriétés de nanoparticules de carbone modèles de la poussière interstellaire. A. Galvez - Thèse de l'Université d'Orléans, 22 Octobre 1999. Markovitsi D. Etude des états électroniques et de la dynamique de relaxation d'un dimère de phtalocyanine de silicium. L. Oddos-Marcel - Thèse de l'Université Joseph Fourier, Grenoble I, 14 Septembre 1998. Markovitsi D. Reconnaissance chirale et énantiosélectivité dans des complexes de van der Waals. K. Le Barbu - Thèse de l'Université Paris XI, Orsay, 29 Janvier 1999. Markovitsi D. Etude du transfert d'énergie dans des systèmes supramoléculaires- effet d'antenne. P. Choppinet - Thèse de l'Université Paris XI, Orsay, 3 Février 2000. Mestdagh J.M. Mise au point d'un dispositif expérimental pour l'étude collisionnelle de complexes ioniques. O. Sublemontier - Mémoire CNAM, 11 Décembre 1998. Millié Ph. (rapporteur) Caractérisation de processus réactionnels élémentaires à l'aide de la théorie des catastrophes. X. Krokidis - Thèse de l'Université Paris VI, 20 Mai 1998. Millié Ph. Etude de petits agrégats mixtes par la méthode de la fonctionnelle de la densité et par des potentiels modèles. M. Bertolus - Thèse de Г Université Paris XI, Orsay, 5 Octobre 1998. Millié Ph. Contribution à la théorie de la fonctionnelle de la densité. Application de la méthode de la transformation d'échelle locale aux matrices densités réduites avec ou sans spin; effets de corrélation et effets de couche. R. Pavlov - Thèse de 1' Université Paris VI, 23 Février 1999. 162 Milli6 Ph. (rapporteur) Etude de la reactivite d'ions solvates en phase gazeuse : approche de la solvatation. G. Van Der Rest - These de l'Ecole Polytechnique, ler Juillet 1999. Milli6 Ph. (rapporteur) Memoire d'habilitation. Anne Boutin - University Paris XI, Orsay, 21 Juillet 1999. Millie" Ph. (rapporteur) Etude experimental et theorique des spectres de vibration de Vetat excite SI d'heterocycles azotes derives du biphenyle. V. de Waele - These de 1'University Lille I, 14 Octobre 1999. Milli6 Ph. (rapporteur) Interaction Cation-Oxygene : Developpement de nouveaux potentiels classiques. X. Peiiole - These de l'Universit6 Paul Sabatier, Toulouse, 5 Novembre 1999. Milli6 Ph. (rapporteur) Etude theorique de la reaction C + CH. M. Boggio-Pasqua - These de l'Universit6 Bordeaux I, 23 Novembre 1999. Milli6 Ph. Etablissement de potentiels d'interaction pour la simulation moleculaire. Application a la prediction des equilibres liquide-vapeur de melanges binaires alcane-molecule multipolaire. J. Delhommelle - These de l'Universite' Paris XI, Orsay, 2 F6vrier 2000. Millie" Ph. Nucleation reactive et transfert de charge comme sondes de la structure electronique des agregats metaliiques. I. Tigneres - These de l'Universit6 de Cergy-Pontoise, 30 Mars 2000. Normand D. Etude du sillage laser: application a Vacceleration d'electrons. F. Dorchies - These de l'Ecole Polytechnique, 17 juin 1998. Normand D. Effets relativistes dans ['interaction laser-plasma a tres hautflux : instability parametriques electroniques et force ponderomotrice. B. Quesnel - These de l'Ecole Polytechnique, 18 juin 1998. Pascale J. (rapporteur) Modelisation semi-classique par invariance adiabatique des collisions reactives ion-molecule. A. Djebri - These de l'Universite Paris VI, 16 Decembre 1998. Pascale J. (rapporteur) Classical trajectory Monte Carlo simulation of ion-atom collisions. A. N. Perumal - Thesis at Banaras Hindu University, Varanasi, India, May 1999. Pascale J. Etude theorique d'un atome ou ion a deux electrons actifs par une methode d'interaction effective. L. Feret - These de l'Universitg Paul Sabatier, Toulouse, 5 Novembre 1999. Poirier M. Etude theorique d'un atome ou ion a deux electrons actifs par une methode d'interaction effective. L. Feret - These de l'Universit6 Paul Sabatier, Toulouse, 5 Novembre 1999. 163 Pradel P. Mise au point d'un dispositif expérimental pour l'étude collisionnelle de complexes ioniques. O. Sublemontier - Mémoire CNAM, 11 Décembre 1998. Reynaud C. Caractérisation de matériaux complexes sur une large gamme spectrale par des techniques optiques et photothermiques; application au carbone amorphe hydrogéné. V. Paret - Thèse de l'Université Paris VI, 21 Janvier 1999. Reynaud C. (rapporteur) Etude des agrégats mixtes bicovalents. C. Ray - Thèse de l'Université Claude Bernard, Lyon, 23 Juin 1999. Reynaud C. Etude de la photoluminescence du silicium nanocristallin : Application astrophysique à l'Emission Rouge Etendue. G. Ledoux - Thèse de L'Ecole Centrale, Lyon, 14 Octobre 1999. Reynaud C. Réactions chimiques hétérogènes induites par pyrolyse laser: application à la synthèse de poudres carbonées et de fullerènes. S. Petcu - Thèse de l'Université Paris XI et de l'Université de Bucarest, 2 Novembre 1999. Reynaud C. (rapporteur) La désorption d'ions négatifs stimulée par impact d'électrons de basse énergie sur les molécules condensées: effets de l'environnement et réactivité induite. M. Lachgar - Thèse de l'Université Paris XI, 25 Février 2000. Schmidt M. Interaction d'agrégats de gaz rares avec un champ laser intense. Dobosz Sandrine - Thèse de l'Université Paris XIII, Villetaneuse, le 30 Novembre 1998 164 Young scientist seminars As a part of a professional education for the PhD students preparing their thesis in our laboratories, the SPAM has since many years established a tradition of regularly held young scientist seminars. Each student must present his research work at least twice during the three year period of his Ph.D. grant. As a rule each seminar has a formal character, is officially announced and the student must defend his work in presence of an exterior senior scientist. Prof. Alain Fuchs, (University of Paris XI, Orsay) and Prof. Jacques Baudon, (University of Paris XIII, Villetaneuse) are in charge as supervising seminar Professors. The seminars are considered as a part of the general educational program proposed by the SPAM to our young scientists. Other trainee programs include job search, language courses, special PhD conferences, etc. The seminar schedule for 1998-2000 is displayed below. Gilles Gr6goire Etude experimental de la separation de charges dans les agregats Nal-solvantn (S= H2O, NH3, CH3CN). 29 Janvier 1998 Aymeric Galvez Analogues terrestres de poussieres carbonees interstellaires. 12Fevrier 1998 Gilles Ledoux he silicium un materiau de passe... et d'avenir. 12 Maxs 1998 Philippe Hering Ionisation multielectronique moleculaire induite par laser: explosion coulombienne et geometrie. 29 Avril 1998 Pierre Villain Etude des proprietes de coherence de phase d'un condensat de Bose-Einstein. 14 Mai 1998 Laurent Le Deroff Generation d'harmoniques d'ordre eleve : qualite dufaisceau et mesure de la coherence spatiale. 25 Juin 1998 Daniele Nutarelli Optiques UV et performances du LEL de Super-ACO. 2 Juillet 1998 Marc Briant Dynamique reactionnelle du baryum sur de gros agregats de gaz rare. ler Octobre 1998 Arnaud Marquette Spectroscopie de fluorescence sur des molecules excitees en couche interne par rayonnement synchrotron. 22 Octobre 1998 Sandrine Dobosz Agregats de gaz rares en champ laser intense. 6 Novembre 1998 165 Olivier Sublemontier Mise au point d'un dispositif experimental pour I'etude collisionnelle de complexes ioniques. 2 Decembre 1998 Sara Vivirito Photoemission processes in laser irradiation of a metal surface. 7 Janvier 1999 Raphael Roux Dynamique et conditions de stabilite du laser a electrons libres de Super-ACO. Fonctionnement avec une cavite RF simple ou double. 11 Janvier 1999 Martine Mayne Nanopoudres ceramiques du systeme Si/C/N. 1. Synthese par pyrolyse laser. 2. Stabilite thermique - Aptitude au frittage. 25 F6vrier 1999 Laurent Henckes Spectroscopie INS : Modelisation par mecanique moleculaire. Application au NMA et au charbon. ler Avril 1999 Stela Petcu Synthese de fullerenes par pyrolyse laser. 13 Avril 1999 Matthieu Gisselbrecht Spectroscopie induite par laser sur des especes atomiques et moleculaires preparees par Rayonnement Synchrotron (RS). 9 Juin 1999 Pierre Villain L'ergodicite revisitee avec les condensats de Bose-Einstein. 17 Juin 1999 Aymeric Galvez Analogues terrestres de poussieres carbonees interstellaires obtenus par pyrolyse laser d'hydrocarbures. 18 Octobre 1999 Laurent Le Deroff Proprietes de coherence de la generation d'harmoniques d'ordre eleve: qualite de faisceau, coherence spatiale et temporelle et application. 22 Novembre 1999 Philippe Hering Contribution a Vetude de la multionisation et de la multifragmentation moleculaire en champ laser intense. 3 Decembre 1999 Daniele Nutarelli Dynamique et performances du laser a electrons libres de Super-ACO avec une cavite RF harmonique a 500 MHZ. 12 Janvier 2000 166 S6bastien Hulin Laser X en recombinaison dans un plasma d'azote cree par OFI. 2 Mars 2000 Stephanie Dar6-Doyen Dimerisation de molecules de colorants dans I'eau : experiences et simulation numerique. 23 Mars 2000 Marc Briant Dynamique reactionnelle du baryum sur gros agregats de gaz rare. 27 Avril 2000 Jean-Franc,ois Hergott Generation d'harmoniques d'ordre eleve : optimisation, focalisation et applications. 12 Mai 2000 Kenichi Ischikawa Explosion d'agregats de gaz rares dans un champ laser intense. 25 Mai 2000 Lionel Poisson + Proprietes collisionnelles desagregats CofHzO),* etFe(H20)n (n=J...9). 15 Juin 2000 167 LIST OF THE LABORATORY STAFF (15 September 2000) DIRECTION NORMAND Didier CEA (33)169 08 24 73 dnorman @drecam.cea.fr BANDURA Jacqueline CEA (33)1 69 08 74 09 [email protected] CROZAT Daniel CEA (33)169 08 65 85 dcrozat@ drecam.cea.fr JACQUART Sandrine CEA (33)169 08 93 91 jacquart @ drecam .cea. fr SERVEURS LASERS FEMTOSECONDE D'OLIVEIRA Pascal CEA (33)1 69 08 82 60 [email protected] FILLON André CEA (33)169 08 46 47 [email protected] GOBERT Olivier CEA (33)1 69 08 94 86 [email protected] GUYADER Didier CEA (33)169 08 46 47 [email protected] MEYNADIER Pierre CEA (33)1 69 08 58 84 meynadier @ drecam. cea. fr PERDRIX Michel CEA (33)1 69 08 58 84 perdrix @ drecam. cea. fr MATIERE SOUS CONDITIONS EXTREMES Interaction Laser Matière en Champ fort CARRE Bertrand CEA (33)169 08 58 40 [email protected] AGOSTINI Pierre CEA (33)169 08 5162 [email protected] AUGUSTE Thierry CEA (33)1 69 08 91 49 [email protected] BOUGEARD Michel CEA (33)1 69 08 25 34 [email protected] BREGER Pierre CEA (33)1 69 08 58 40 [email protected] CAPRIN Eric CEA (33)1 69 08 25 34 CHERET Michel CEA (33)1 69 08 65 51 mcheret @ drecam .cea. fr CORNAGGIA Christian CEA (33)1 69 08 96 65 [email protected] DOBOSZ Sandrine CEA (33)1 69 08 63 40 [email protected] GONTIER Yves CEA (33)169 08 3163 [email protected] HERGOTT J.François cm (33)169 08 63 39 [email protected] HULIN Sébastien CFR (33)1 69 08 63 39 [email protected] MERDn Hamed P.doc (33)1 69 08 51 63 [email protected] MONOT Pascal CEA (33)1 69 08 91 49 [email protected] PASCALE Jean CEA (33)1 69 08 51 61 [email protected] PAUL P. Marie MRES (33)1 69 08 69 01 [email protected] QUAGLIA Luca MRES (33)1 69 08 63 40 quaglia@ spam.saclay.cea.fr SALIERES Pascal CEA (33)1 69 08 63 39 [email protected] Matière à Haute Densité d'Energie BLENSKI Thomas CEA (33)1 69 08 96 64 [email protected] ISHIKAWA Kenichi P. Doc (33)1 69 08 58 88 [email protected] LAGADEC Hervé CEA (33)1 69 08 22 45 [email protected] PAIN J. Christophe MRES (33)1 69 08 58 88 [email protected] POIRIER Michel CEA (33)1 69 08 46 29 [email protected] THAIS Frédéric CEA (33)1 69 08 65 14 [email protected] Groupe d'applications des Plasmas SCHMIDT Martin CEA (33)1 69 08 26 57 [email protected] BOUCHON Mathilde STAG. (33)1 69 08 57 03 bouchon @ drecam.cea.fr CECCOTTI Tiberio P. Doc (33)1 69 08 26.57 [email protected] LE DEROFF Laurent Coll. Ext (33)1 69 08 57 03 [email protected] SEGERS Marc CTCI (33)1 69 08 57 03 [email protected] SUBLEMONTIER Olivier CEA (33)1 69 08 26 57 osublemontier @ drecam.cea. fr 169 PHYSICOCHIMIE D'EDIFICES MOLECULAIRES Photophysique photochimie VISTICOT Jean-Paul CEA (33)169 08 68 43 [email protected] DIMICOLI Iliana CEA (33)169 08 63 75 dimicoli @ drecam.cea.fr BRIANT Marc CFR (33)169 08 50 66 [email protected] CALVO MUÑOZ M. luisa MRES (33)1 69 08 94 27 [email protected] FOüRNIER P.Richard CEA (33)1 69 08 65 50 fournier @ drecam .cea. fr GAVEAU M.André CEA (33)1 69 08 50 66 [email protected] GUSTAVSSON Thomas CNRS (33)169 08 93 09 [email protected] LEPETIT Fabien CEA (33)1 69 08 24 45 [email protected] MARKOVITSI Dimitra CNRS (33)169 08 46 44 [email protected] MARGUET Sylvie CNRS (33)1 69 08 62 83 [email protected] MESTDAGH J.Michel CNRS (33)169 08 25 45 jmestdagh @ santamaria.saclay.cea.fr MONS Michel CEA (33)1 69 08 20 01 [email protected] PIUZZI François CEA (33)1 69 08 30 79 [email protected] POISSON Lionel DEA (33)1 69 08 25 45 [email protected] TARDIVEL Benjamin CEA (33)1 69 08 33 95 [email protected] TRANTHI ThuHoa CNRS (33)1 69 08 49 33 [email protected] WLOSIK Alexandre ADEME (33)1 69 08 94 27 wlosik @ drecam.cea. fr Poudres Laser/Grains Interstellaires REYNAUD Cécile CEA (33)169 08 69 16 [email protected] ARMAND Xavier CEA (33)1 69 08 61 27 [email protected] GUILLOIS Olivier CEA (33)1 69 08 91 87 [email protected] HENCKES Laurent CFR (33)1 69 08 67 49 [email protected] HERLIN BOIME Nathalie CEA (33)1 69 08 36 84 her lin @drecam. cea.fr MAYNE Martine CEA (33)169 08 52 62 mayne @ drecam. cea. fr PORTERAT Dominique CEA (33)1 69 08 63 32 [email protected] TENEGAL François P. Doc (33)1 69 08 31 39 ténégal @drecam .cea.fr Chimie Théorique [email protected] DOGNON Jean Pierre CEA (33)1 69 08 37 14 [email protected] ANGELE Christian CEA (33)1 69 08 28 55 [email protected] BRENNER Valérie CEA (33)1 69 08 76 42 [email protected] de PUJO Patrick CEA (33)1 69 08 80 37 [email protected] GILARD Françoise P. Doc (33)1 69 08 37 40 [email protected] MILLIE Philippe С Seien. (33)1 69 08 63 42 [email protected] SOUDAN Jean Maik CEA (33)1 69 08 37 40 [email protected] THOMAS Anne Laure CFR (33)169 08 37 88 althomas @ olive, saclay.cea.fr Rayonnement Synchrotron MORIN Paul CEA (33)164 46 8124 [email protected] ALOISE Stéphane MRES (33)164 46 80 96 aloise @ lure.u-psud. fr CEOLIN Denis MRES (33)164 46 80 96 ceolin @ lure, u-psud. fr COUPRIE M.Emmanuelle CEA (33)164 46 80 44 couprie @ lure, u-psud.fr DENTNNO Giovanni P. Doc (33)164 46 81 16 [email protected] GARZELLA David CEA (33)164 46 80 91 [email protected] GISSELBRECHT Mathieu MRES (33)1 64 46 80 96 [email protected] GUILLEMIN Renaud MRES (33)164 46 81 19 guillemin @ lure, u-psud.fr HIRSCH Mathias MRES (33)1 64 46 80 44 hirsch @ lure, u-psud. fr LECLERCQ Nicolas CEA (33)164 46 8188 leclercq @lure.u-psud.fr LEGUEN Karine MRES (33)164 46 8188 leguen @ lure.u-psud.fr MEYER Michael CNRS (33)164 46 80 97 [email protected] NAHON Laurent CEA (33)164 46 88 60 nahon @ lure.u-psud.fr RENAULT Eric P.Doc (33)164 46 80 44 [email protected] SIMON Marc CEA (33)1 64 46 80 97 [email protected] 170