Book of Abstracts

5th International Workshop on Electrostatic Storage Devices

June 17 – 21, 2013 Max-Planck Institute for Nuclear Physics Heidelberg, Germany Max Planck Institute for Nuclear Physics Saupfercheckweg 1 D-69117 Heidelberg Germany June 2013

2 Preface

The dynamic development of electrostatic storage devices for ion beams is creating new experimental options for research on large and small molecules, highly charged ions, and atomic clusters. The growing capabilities of these devices greatly expand the advantages of using stored ion beam methods by the availability of cryogenic temperatures, high molecular masses, and high- quality low-velocity ion beams. Furthermore, new opportunities arise for employing laser sources in a wide spectral range and for merged-beam collision experiments, ring-internal targets, and advanced particle detection techniques. Thus, new possibilities are created for sensitive experiments on collisional and internal rearrangements in complex atomic-scale systems, and in fields such as mass spectrometry and weak interactions in nuclei. Accompanying these advances, International Workshops on Electrostatic Storage Devices were held in Eilat, Israel (2005), Stockholm, Sweden (2007), Aarhus, Denmark (2009) and Gatlinburg, USA (2011). In the line of the previous meetings, the Heidelberg Workshop ESD 2013 is devoted to progress in the development of instruments and procedures as well as to research with low-energy stored ion beams – expanding to an increasingly broad range of scientific areas as the experimental options evolve. The following topics will be addressed by ESD 2013: – Intra-molecular energy and charge propagation and rearrangement – Vibrational autodetachment in complex molecular ions – Spectroscopy with fast ion beams, including new wavelength regimes – Merged beams experiments with stored ions – Gas-phase studies of ionic processes in organic chemistry – Low-energy ion storage and nuclear physics – Stored ion beam techniques in mass spectrometry – Particle detectors for low-energy ion beams – Sources of cold and complex molecular ions – Development of low-energy stored ion beam facilities – Ionic and molecular processes in atmospheric, astrophysical and plasma research

We gratefully acknowledge the support of the meeting by the Max Planck Institute for Nulcear Physics, the Max Planck Society, and the ExtreMe Matter Institute, EMMI. Our thanks go to all authors contributing to this Book of Abstracts and to the scientific program of ESD 2013.

On behalf of the Local Organizing Committee Andreas Wolf

3 International Program Advisory Committee Toshiyuki Azuma, Atomic, Molecular & Optical Physics Laboratory, RIKEN, Tokyo, Japan Steen Brøndsted Nielsen, Department of Physics and Astronomy, Aarhus University, Denmark Robert Continetti, Department of Chemistry and Biochemistry, University of San Diego, USA Michael Fogle, Physics Department, Auburn University, USA Oded Heber, Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Israel Mark Johnson, Department of Chemistry, Yale University, Connecticut, USA Serge Martin, LASIM, Université de Lyon, France Henning Schmidt, Atomic Physics, Department of Physics, Stockholm University, Sweden Andreas Wolf, Max Planck Institute for Nuclear Physics, Heidelberg, Germany

Local Organizing Committee Andreas Wolf (Chair) Klaus Blaum Manfred Grieser Kristian Haberkorn Robert von Hahn Claude Krantz Holger Kreckel Michael Lange Oldřich Novotný Claus-Dieter Schröter

Conference Web Page http://www.mpi-hd.mpg.de/blaum/events/esd2013

ESD 2013 Sponsors

ExtreMe Matter Institute EMMI www.mpi-hd.mpg.de www.mpg.de/ www.gsi.de/emmi

4 ESD 2013

Conference Program Times include 5 min of discussion Monday, June 17

8:45 Bus departure from Conference Bus Stops (Heidelberg Main Station and Bahnhofstrasse/Landhausstrasse)

9:00- 9:40 Registration (MPIK Library Building, Foyer)

9:40- 9:45 Opening

Session 1: Electrostatic Ion Storage

9:45-10:30 L. H. Andersen I 1 Ions in the gas phase, studied in electrostatic ion-storage rings

10:30-11:15 Coffee break and registration

Session 2: Macromolecular Fragmentation and Spectroscopy

11:15-11:45 T. Schlathölter I 2 Ionization and fragmentation of complex biomolecules upon interaction with keV ions and energetic photons 11:45-12:15 R. Antoine I 3 Multiphoton dissociation of trapped macromolecular ions at the single-molecule level 12:15-12:35 J. A. Wyer C 25 Gas-phase spectroscopy of heme ions

12:35-14:30 Lunch (EMBL canteen) + coffee (Foyer)

Session 3: Spectroscopy and Relaxation Dynamics

14:30-15:00 L. Chen I 4 Fast radiative cooling of Anthracene observed in the Miniring

15:00-15:30 K. Støchkel I 5 Spectroscopy of Firefly Oxyluciferin Anions

15:30-15:50 C. Johnson C 10 Charge separation and the early stages of dissolution in hydrated salt clusters 15:50-16:30 Coffee break

Session 4: Nuclear Decays and Isotopes

16:30-17:00 M. Hass I 6 β−ν Correlation Precision Measurements in an Electrostatic Trap

17:00-17:30 F. Wienholtz I 7 ISOLTRAP’s multi-reflection time-of-flight mass separator/spectrometer 17:30-20:00 Poster session + Welcome

20:00 Bus departure from MPIK

5 Tuesday, June 18

8:45 Bus departure from Conference Bus Stops (Heidelberg Main Station and Bahnhofstrasse/Landhausstrasse)

Session 5: Reactions and Spectroscopy with Ion Beams

9:15- 9:45 R. E. Continetti I 8 Studies of molecular reaction dynamics using a cryogenic electrostatic ion beam trap

9:45-10:15 L. M. Nielsen I 9 Ion beam spectroscopy of DNA strands

10:15-10:45 H. Shiromaru I 10 Study on carbon cluster and polyyne anions in TMU E-ring

10:45-11:15 Coffee break

Session 6: Ionic Reactions

11:15-11:55 F. Arnold I 11 Upper atmospheric Ions and Ion processes – Implications for trace gases and aerosol

11:55-12:25 X. Urbain I 12 Ion-neutral merged beams experiments of astrophysical interest

12:25-12:45 T. Best C 3 Probing reactive processes in a 22pole Ion Trap with a Multicycle Reflectron based TOF detector 12:45-14:30 Lunch (EMBL canteen) + coffee (Foyer)

Session 7: Storage Rings I

14:30-15:00 Y. Enomoto I 13 Development of a cryogenic electrostatic ring in RIKEN

15:00-15:30 M. Gatchell I 14 First results from the Double ElectroStatic Ion-Ring ExpEriment, DESIREE 15:30-16:00 R. von Hahn I 15 Status of the Cryogenic Storage Ring CSR

16:00-18:30 Poster session and coffee

18:30 Bus departure from MPIK

6 Wednesday, June 19

8:45 Bus departure from Conference Bus Stops (Heidelberg Main Station and Bahnhofstrasse/Landhausstrasse)

Session 8: Mass Spectrometry and New Approaches

9:15- 9:55 O. Trapp I 16 Mass Spectrometry as Indispensible Tool to Investigate Catalytic Reactions 9:55-10:25 A. Fleischmann I 17 Micro-calorimetric detectors for fast molecules and fragments

10:25-10:45 J. Matsumoto C 14 Construction of a tabletop electrostatic storage ring

10:45-11:15 Coffee break

Session 9: Time-Resolved Photo-Induced Dynamics

11:15-11:45 L. Belshaw I 18 Observation of Ultrafast Intra-Molecular Charge Migration in a Biomolecule 11:45-12:25 R. Moshammer I 19 Ion beam interactions with ultra-short laser pulses

12:25-12:50 C. Riehn I 20 Laser photofragmentation and ultrafast time-resolved dynamics of trapped complex molecular ions 12:50-14:30 Lunch (EMBL canteen) + coffee (Foyer)

Session 10: Storage Rings II

14:30-15:00 R. Brédy I 21 Status at Mini-Ring: recent progress and perspectives

15:00-15:30 H. B. Pedersen I 22 The new electrostatic storage ring SAPHIRA

15:30 Conference excursion

15:45 Bus departure from MPIK

18:45 Dinner at Klosterschenke Neuburg

about 22:30 Return to Heidelberg

7 Thursday, June 20

8:45 Bus departure from Conference Bus Stops (Heidelberg Main Station and Bahnhofstrasse/Landhausstrasse)

Session 11: Photoreactions and Decays

9:15- 9:55 R. Wester I 23 Photodetachment spectroscopy of trapped anions

9:55-10:25 S. Schippers I 24 Perspectives for Investigations of Chiral Systems with Ion Beams

10:25-10:45 V. Chandrasekaran C 5 Delayed emission in small carbon cluster anions

10:45-11:15 Coffee break

Session 12: Complex Ionic Structure

11:15-11:45 T. Tanabe I 25 Molecular structure conversion of stored monoanions in electrostatic storage ring

11:45-12:15 S. Menk I 26 Electron autodetachment of sulfur hexafluoride anions

12:15-12:35 M. Ji C 9 The prompt and delayed dissociation of Pyrene cation in the Miniring

12:35-14:30 Lunch (EMBL canteen) + coffee (Foyer)

Session 13: Mass Spectrometry and Ion Bunches

14:30-15:00 D. Grinfeld I 27 Orbitrap Mass Spectrometry

15:00-15:30 M. Rosenbusch I 28 Energy transfer between ion clouds in multi-reflection ion traps

15:30-15:50 M. Lange C 13 Limits to the Persistence of Self-Synchronized Bunches in an Electrostatic Ion Beam Trap

16:00 Guided tour to MPIK laboratories

19:00 Bus departure from MPIK

8 Friday, June 21

8:45 Bus departure from Conference Bus Stops (Heidelberg Main Station and Bahnhofstrasse/Landhausstrasse)

Session 14: Large Molecules and Metal Clusters

9:15- 9:35 M. H. Stockett I 29 Low center-of-mass energy collisions between Polycyclic Aromatic Hydrocarbon ions and noble gases 9:35-10:00 M. Tombers I 30 Isolated Transition Metal Clusters: Formation and Cold Ion Trap Investigation for their magnetic properties 10:00-10:20 C. Breitenfeldt C 4 Investigation of radiative cooling of small metal cluster anions by laser-induced electron detachment 10:20-10:50 Coffee break

Session 15: Photoprocesses and Molecular Stability

10:50-11:20 A. V. Bochenkova I 31 Photo-induced non-adiabatic dynamics in biosystems: intrinsic dual photoresponse of anionic chromophores and selective tuning by proteins

11:20-11:50 Y. Toker I 32 The effect of a localized charge on the structure and stability of Van-der-Waals clusters

11:50-13:15 Lunch (EMBL canteen) + coffee (Foyer)

Session 16 13:15-14:00 Concluding remarks, closing the conference

Bus departure from MPIK Departure time to be announced

9 10 ESD 2013

List of posters

C 1 J. Alexander Modeling electron and energy transfer processes in collisions between ions and Polycyclic Aromatic Hydrocarbon molecules J. Alexander, T. Chen, B. Forsberg, A. Pettersson, M. Gatchell, H. Cederquist, H. Zettergren

C 2 A. Becker A Detector for 3D Molecular Fragmentation Imaging at the Cryogenic Storage Ring A. Becker, C. Krantz, O. Novotný, K. Spruck, X. Urbain, S. Vogel and A. Wolf

C 3 T. Best Probing reactive processes in a 22pole Ion Trap with a Multicycle Reflectron based TOF detector E. Endres, D. Hauser, O. Lakhmanskaya, T. Best, and R. Wester

C 4 C. Breitenfeldt Investigation of radiative cooling of small metal cluster anions by laser-induced electron detachment C. Breitenfeldt, K. Blaum, M. Froese, S. George, M. Lange, S. Menk, L. Schweikhard, A. Wolf

C 5 V. Chandrasekaran Delayed emission in small carbon cluster anions V. Chandrasekaran, H. Rubinstein, B. Kafle, Y. Toker, O. Heber, M. L. Rappaport, D. Schwalm and D. Zajfman

C 6 M. F. Gharaibeh K-Shell Photoionization in the Nitrogen Isonuclear Sequence M. F. Gharaibeh, J. M. Bizau, D. Cubaynes, S. Guilbaud, N. El Hassan, M. M. Al Shorman, C. Miron, C. Nicolas, E. Robert, I. Sakho, C. Blancard and B. M. McLaughlin

C 7 D. Grinfeld Space-Charge Dynamics in a Multi-Reflection Ion Trap A. Giannakopulos, D. Grinfeld, I. Kopaev, A. Makarov, M. Monastyrskiy, M. Skoblin

C 8 F. Grussie A versatile ion-neutral collision setup for the CSR F. Grussie, F. Berg, M. Grieser, A. P. O’Connor, and H. Kreckel

C 9 M. Ji The prompt and delayed dissociation of Pyrene cation in the Miniring M. Ji, C. Ortéga, R. Brédy, J. Bernard, L. Chen, G. Montagne, A. Cassimi, Y. Ngono-Ravache, C. Joblin and S. Martin

11 C 10 C. Johnson Charge separation and the early stages of dissolution in hydrated salt clusters C. Johnson, C. Leavitt and M. Johnson

C 11 T. Kolling A Laser Vaporization (LVAP) metal ion cluster source T. Kolling, M. Tombers and G. Niedner-Schatteburg

C 12 H. Kreckel Combining experimental techniques for comprehensive case studies of molecular astrophysics H. Kreckel, F. Grussie, A.P. O’Connor, A. Becker, C. Krantz, O. Novotny, and A. Wolf

C 13 M. Lange Limits to the Persistence of Self-Synchronized Bunches in an Electrostatic Ion Beam Trap M. Lange, K. Blaum, C. Breitenfeldt, M. Froese, S. George, M. Grieser, S. Menk, L. Schweikhard, A. Wolf

C 14 J. Matsumoto Construction of a tabletop electrostatic storage ring J. Matsumoto, K. Gouda and H. Shiromaru

C 15 Y. Nakano Status of the injection beamline for the cryogenic electrostatic storage ring at RIKEN Y. Nakano, T. Masunaga, Y. Enomoto and T. Azuma

C 16 O. Novotný Calorimeter detector for fragmentation studies at CSR O. Novotný, L. Gamer, C. Krantz, A. Pabinger, C. Pies, C. Enss, D. W. Savin, A. Fleischmann, and A. Wolf

C 17 C. Ortéga Measurement of PAH Kinetic Energy Release (KER) in the Mini-Ring C. Ortéga, R. Brédy, M. Ji, J. Bernard, G. Montagne, A. Cassimi, Y. Ngono-Ravache, C. Joblin, L. Chen and S. Martin

C 18 A. Prabhakaran Electron Velocity Map Imaging in an Electrostatic Ion Beam Trap A. Prabhakaran, M. Rappaport, Y. Toker, O. Heber, D. Schwalm, D. Zajfman

C 19 A. Prygarin Monte Carlo simulations of β−ν Correlation Precision Measurements of 6He+ in an Electrostatic Trap M. Hass, S. Vaintraub, A. Prygarin, A. Dhal, O. Heber, T. Hirsh, D. Melnik, T. Kong, M. L. Rappaport, G. Ron, D. Schwalm, T. Segal, D. Zajfman, K. Blaum

C 20 H. Rubinstein A Cryogenic Electrostatic Ion Beam Trap to study molecular ions and clusters at 4 – 300 K H. Rubinstein, M. Rappaport, Y. Toker, V. Chandrasekaran, O. Heber, D. Schwalm and D. Zajfman

12 C 21 K. Spruck Development and tests of a single particle counting detector for the CSR K. Spruck, A. Becker, C. Krantz, A. Müller, O. Novotný, A. Wolf and S. Schippers

C 22 K.E. Stiebing Status of FLSR K. E. Stiebing, D. Tiedemann, R. Dörner, F. King, A. Jung, M. Völp and A. Papash

C 23 S. Vaintraub Design of a new position and energy sensitive electron detector S. Vaintraub, M. Hass, H. Edri, A. Prygarin and T. Segal

C 24 S. Vogel Status of the low-energy electron cooler for the Cryogenic Storage Ring S. Vogel, K. Blaum, C. Krantz, A. Shornikov, and A.Wolf

C 25 J. A. Wyer Gas-phase spectroscopy of heme ions J. A. Wyer and S. Brøndsted Nielsen

I 14 M. Gatchell First results from the Double ElectroStatic Ion-Ring ExpEriment, DESIREE M. Gatchell, H. T. Schmidt, J. D. Alexander, G. Andler, M. Björkhage, M. Blom, L. Brännholm, E. Bäckström, T. Chen, W. Geppert, P. Halldén, D. Hanstorp, F. Hellberg, A. Källberg, M. Larsson, S. Leontein, L. Liljeby, P. Löfgren, S. Mannervik, A. Paál, P. Reinhed, K-G. Rensfelt, S. Rosén, F. Seitz, A. Simonsson, M. H. Stockett, R. D. Thomas, H. Zettergren and H. Cederquist

I 29 M. H. Stockett Low center-of-mass energy collisions between Polycyclic Aromatic Hydrocarbon ions and noble gases M. H. Stockett, J. D. Alexander, U. Bērziņš, T. Chen, K. Farid, M. Gatchell, A. Johansson, K. Kulyk, H. T. Schmidt, H. Zettergren and H. Cederquist

13 14 Abstracts of Invited Talks

15 16 ESD 2013 Invited Talk No 1 I 1

Ions in the gas phase, studied in electrostatic ion-storage rings

Lars H. Andersen

Department of Physics and Astronomy University of Aarhus DK-8000 Aarhus C

E-mail: [email protected]

Electrostatic ion-storage rings have proven to be valuable tools in studying ions under vacuum conditions. The ELectrostatic Ion Storage ring in Aarhus (ELISA) was first described in the literature in 1997 [1], at about the same time as the design of a resonator-type ion trap was reported at the Weizmann Institute [2]. Both ion-trapping devices are being used with great success [3]. The traps and rings offer a number of advantages in comparison with conventional single-pass accelerator based techniques. The ability to follow a species over time, for example after excitation by a laser, is of immense importance. Thereby reaction channels may be sorted according to their ‘reaction-time’. Direct electron emission, for example, happens essentially prompt compared to the oscillation/revolution time in the storage device, whereas statistical fragmentation in a hot ground state typically happens much slower.

In my presentation I will focus on action-absorption spectroscopy. Over the years photo-absorption properties of a number of bio-chromophores have been studied. To achieve this, the electrospray technique [4] and also the necessary laser technology with tunable wavelength [5] was introduced at ELISA. The bio-chromophore of the Green Fluorescent Protein (GFP) was our first system under investigation [5], and new aspects of its remarkable photo- physical properties are still being discovered theoretically [6] as well as experimentally [7]. Of particular interest here is the role of electronically excited bound states along with unbound resonance states.

Entire rings cooled to very low temperatures (Stockholm, Heidelberg) are under final construction, and new rings (Aarhus) have been constructed for fs-time resolved studies of stored ions and as a target ring for UV light from the new ASTRID2 synchrotron facility. Exciting times with ion-storage rings are still ahead of us!

References [1] S. P. Møller. Nucl. Instr. and Meth. A 394, 281 (1997) [2] D. Zajfman et al.. Phys. Rev. A 55, R1577 (1997) [3] L.H. Andersen, O. Heber, and D. Zajfman. J. of Phys. B. 37, R57 - R88 (2004) [4] J. U. Andersen et al. Rev. Sci. Instrum. 73, 1284 (2002) [5] S. B. Nielsen, A. Lapierre, J. U. Andersen, U. V. Pedersen, S. Tomita, and L.H. Andersen. Phys. Rev. Lett. 87, 228102 (2001) [6] A. V. Bochenkova, and L. H. Andersen. Faraday Discuss. DOI: 10.1039/C3FD20150C (2013) [7] Y. Toker, D. B. Rahbek, B. Klærke, A. V. Bochenkova, and L. H. Andersen. Phys. Rev. Lett. 109, 128101 (2012)

17 ESD 2013 Invited Talk No 2 I 2

Ionization and fragmentation of complex biomolecules upon interaction with keV ions and energetic photons

Thomas Schlathölter

Atomic and Molecular Physics Group, University of Groningen, Zernikelaan 25 9747AA Groningen, The Netherlands E-mail: [email protected]

Spectroscopic studies of large biomolecules are often performed in the liquid phase, where these complex systems unfold their activity. Over the last years, however, enormous interest in the physics of gas-phase biomolecular systems has developed, mainly for three reasons: i) the importance to distinguish intrinsic molecular properties from effects of the chemical environment; ii) the possibility to investigate fundamental interactions and microsolvation; and iii) the need of gas-phase data to test quantum chemical calculations. The response of isolated biomolecules upon VUV and soft X-ray photoabsorption and keV ion impact is of great interest i.e. in the context of astrobiology and radiobiology. Key questions concern ion chemistry in the interstellar medium, the possibility of transport of intact gas phase biomolecules from space to earth and molecular mechanisms underlying biological radiation damage. We have developed a versatile tandem mass spectrometer equipped with an electrospray ionization source and a radiofrequency ion trap which can be easily interfaced with synchrotron beamlines and keV ion facilities. In first studies we could show, that keV ion and VUV photon induced fragmentation of the peptide leucine enkephalin induce mainly sidechain losses [1,2]. This is fundamentally different from conventional mass spectrometric techniques where mostly backbone scission is observed. Investigation of fragment yields of protonated YGnF peptides as a function of VUV photon energy and peptide length revealed, that this sidechain loss is due to fast hole migration from the backbone to the Y and F termini [3]. Moving from VUV photons to soft X-rays near the C K-edge, it is even possible to directly assign fragmentation channels to specific electronic transitions some of which are site specific. For instance, C 1s → π* excitations in the leucine encephalin aromatic side chains lead to relatively little fragmentation, whereas such excitations along the peptide backbone induce strong fragmentation [4]. In the context of biological radiation damage, we have performed a comparative study of oligonucleotide damage induced by keV ions or energetic photons. The experiments on protonated GCAT confirmed a finding from gas-phase DNA building blocks: deoxyribose seems to be involved in most fragmentation channels. The fragment masses observed here, however, are typically unobserved in gas-phase studies [5].

References [1] S. Bari, R. Hoekstra, T. Schlathölter, Phys. Chem. Chem. Phys. 12 (2010) 3376 [2] S. Bari, O. Gonzalez–Magaña, G. Reitsma, J. Werner, S. Schippers, R. Hoekstra, T. Schlathölter, J. Chem. Phys. 134 (2011) 024314 [3] O. Gonzalez–Magaña, G. Reitsma, S. Bari, R. Hoekstra, T. Schlathölter, Phys. Chem. Chem. Phys. 14 (2012) 4351 [4] O. Gonzalez-Magaña, G. Reitsma, M. Tiemens, L. Boschman, R. Hoekstra, T. Schlathölter, J. Phys. Chem. A 116 (2012) 10745 [5] O. Gonzalez-Magaña, M. Tiemens, G. Reitsma, L. Boschman, M. Door, S. Bari, R. Hoekstra, P. O. Lahaie, J. R. Wagner, M. A. Huels, T. Schlathölter, Phys. Rev. A 87 (2013) 032702

18 ESD 2013 Invited Talk No 3 I 3

Multiphoton dissociation of trapped macromolecular ions at the single-molecule level

R. Antoine, T. Doussineau, P. Dugourd and F. Calvo

1 Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France

E-mail: [email protected]

A new experimental setup to simultaneously measure the mass and charge of "megadalton" objects (macroions consisting of tens of thousands of atoms) produced by electrospray ionization, has been implemented. This assembly uses the principle of the charge detection combined to time-of-flight measurements on single ions. In addition to its strong analytical potential for mass characterization of nanoparticles,[1] an electrostatic trap has recently been implemented to conduct photofragmentation experiments on single macroions.[2]

In this work, we have coupled a CO2 laser to the ion trap to achieve infrared multiphoton dissociation (IRMPD) and determine the activation unimolecular dissociation energy of macropolymers such as entire DNAs.[3] Single ions are stored (by making roundtrips into the trap) for several tens of milliseconds. These trapped ions are then irradiated by CO2 laser and fragmented by heating due to vibrational multiphoton IR activation. The activation energy associated with the dissociation of macroions can be determined by an Arrhenius-type approach by analyzing a large set of traces of individual ions to build a histogram of the frequency distribution of dissociation rates.

The laser-induced decay of ethylene oxide polymer ions of megadalton size has been studied in the multiphoton IR excitation regime, fragmentation products of individual ions being monitored over long times by a trapping device.[4] The experiment reveals several fragmentation pathways having distinct signatures at the single molecule level, that which would not be accessible from studies based on statistically averaged reaction rates only. The observations are supported by dedicated molecular simulations based on a coarse-grained model, which further highlight the role played by continuous heating in such out-of-equilibrium conditions. In particular, both experiment and modeling indicate that the dissociation kinetics depends non linearly on heating rate.

References

[1] Doussineau, T.; Bao, C. Y.; Antoine, R.; Dugourd, P.; Zhang, W.; D'Agosto, F.; Charleux, B., ACS Macro Lett., 1, 414-417, (2012). [2] Doussineau, T.; Bao, C. Y.; Clavier, C.; Dagany, X.; Kerleroux, M.; Antoine, R.; Dugourd, P., Rev. Sci. Instrum., 82, 084104, (2011). [3] Doussineau, T.; Antoine, R.; Santacreu, M.; Dugourd, P., J. Phys. Chem. Lett., 3, 2141-2145, (2012). [4] Antoine, R.; Doussineau, T.; Dugourd, P.; Calvo, F., Phys. Rev. A, 87, 013435, (2013).

19 ESD 2013 Invited Talk No 4 I 4

Fast radiative cooling of Anthracene observed in the Miniring

L. Chen1, J. Bernard1, R. Brédy1, B. Concina1, C. Joblin2,3, M. Ji1, C. Ortega1 and S. Martin1

1Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France 2Université de Toulouse, UPS-OMP, IRAP, Toulouse, France 3 CNRS, IRAP, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4, France E-mail: [email protected]

+ Fast radiative cooling of anthracene (C14H10) was studied using a compact electrostatic + storage ring, called Miniring [1,2]. Hot (C14H10) molecules from an electron cyclotron resonance ion source were accelerated to 10 keV and stored in the Miniring. After a given storage and cooling time (several ms), the punch of stored ions was excited along one of the straight sections (of 9.2 cm long) by a nanosecond laser pulse (3.55 eV). Owing to the compactness of the ring, neutral fragments lost at the opposite straight section were detected with a channeltron detector from the very first microseconds. The neutral decay curves (fig.1) recorded with laser pulse fired at tlaser=4, 5, 6, 8 ms were fitted using a simple unimolecular statistical dissociation model in order to extract the internal energy distributions (fig.2) of the excited molecular ensemble.

5000 4 ms 4000 5 ms 6 ms 8 ms

3000

s

t

n

u

o c

2000

1000

010 20 30 40 50 time (µs) fig.1 neutral decay curves fig.2 internal energy distributions

From fig.2, by subtracting the energy of the absorbed photon, we obtained the time evolution of the internal energy distribution of the stored molecules before laser excitation. Mean radiative decay rates of about 120 s-1 to 250 s-1 were estimated for internal energies in the range from 6.6 eV to 6.8 eV. Such a high decay rate is by two orders of magnitude larger than the infrared (IR) emission cooling rate expected for vibrational transitions. It is attributed to fluorescence from thermally excited electrons. This fast radiative cooling mechanism may have important implications in astrophysics concerning the lifetime and the critical size of polycyclic aromatic hydrocarbons (PAHs) in interstellar conditions.

References [1] J. Bernard et al., Rev. Sci. Instrum. 79, 075109 (2008) [2] S. Martin, J. Bernard, R. Brédy, B. Concina, C. Joblin, M. Ji, C. Ortega and L. Chen, Phys. Rev. Lett., 110, 063003 (2013)

20 ESD 2013 Invited Talk No 5 I 5

Spectroscopy of Firefly Oxyluciferin Anions

K. Støchkel1

1 Department of Physics and Astronomy Aarhus University Ny Munkegade 120 DK-8000 Aarhus C

E-mail: [email protected]

A complete understanding of the physics underlying the varied colors of firefly bioluminescence remains elusive because it is difficult to disentangle different enzyme– lumophore interactions. Experiments on isolated ions are useful to establish a proper reference when there are no microenvironmental perturbations. Here, we use action spectroscopy to compare the absorption by the firefly oxyluciferin lumophore isolated in vacuo and complexed with a single water molecule. While the process relevant to bioluminescence within the luciferase cavity is light emission, the absorption data presented here provide a unique insight into how the electronic states of oxyluciferin are altered by microenvironmental perturbations. For the bare ion we observe broad absorption with a maximum at 548 ± 10 nm, and addition of a water molecule is found to blue-shift the absorption by approximately 50 nm (0.23 eV). Test calculations at various levels of theory uniformly predict a blue-shift in absorption caused by a single water molecule, but are only qualitatively in agreement with experiment highlighting limitations in what can be expected from methods commonly used in studies on oxyluciferin. Combined molecular dynamics simulations and time-dependent density functional theory calculations closely reproduce the broad experimental peaks and also indicate that the preferred binding site for the water molecule is the phenolate oxygen of the anion. Predicting the effects of microenvironmental interactions on the electronic structure of the oxyluciferin anion with high accuracy is a nontrivial task for theory, and our experimental results therefore serve as important benchmarks for future calculations.

References K. Støchkel, C. N. Hansen, J. Houmøller, L. Munksgaard Nielsen, K. Anggara, M. Linares, P. Norman, F. Nogueira, O. V. Maltsev, L. Hintermann, S. Brøndsted Nielsen, P. Naumov and B. F. Milne. J. Am. Chem. Soc, DOI: 10.1021/ja311400t

21 ESD 2013 Invited Talk No 6 I 6

 Correlation Precision Measurements in an Electrostatic Trap

M. Hass1, S. Vaintraub1,2, A. Prygarin1, A. Dhal1, O. Heber1,T. Hirsh2,. D. Melnik2, T. Kong1, M.L Rappaport1, G. Ron4, D. Schwalm1,3, T. Segal4, D. Zajfman1, K. Blaum3

1 Weizmann Institute of Science, Rehovot, Israel 2 Soreq Nuclear Research Center, Yavne 81800, Israel 3 Max-Planck-Institut für Kernphysik, D-69117 Heidelberg, Germany 4 The Hebrew University, Jerusalem, Israel

E-mail: [email protected]

One of the possibilities to study fundamental interactions and the underlying symmetries is via precision measurements of the parameters of beta decay of trapped radioactive atoms and ions. For example, determining the beta-neutrino angular correlation coefficient in a trap can probe the minute experimental signal that originates from possible tensor or scalar terms in the weak interaction, thus probing possible new physics of beyond-the-standard-model nature. For precision measurements of this correlation, traps are mandatory since the recoiling nuclei, subsequent to the beta decay, are at sub-keV energies. We have embarked on an experimental scheme to establish a novel experimental set-up to study the beta-neutrino correlation by studying the decay of the trapping light radioactive ion beam inside an Electrostatic Ion Beam Trap. This method exhibits several advantages compared to other commonly used trapping schemes in terms of concept, efficiency and ease of operation. The first nuclide under study is 6He, to be produced using use neutron-induced reactions and subsequent ionization in an electron ion beam source/trap (EBIT) for ionization. The 6He+ radioisotopes will be stored in an electrostatic ion beam trap (EIBT), commonly used in atomic and molecular physics. The entire apparatus has been built at the Weizmann Institute. The method, the results of commissioning runs and future plans will be discussed.

22 ESD 2013 Invited Talk No 7 I 7

ISOLTRAP’s multi-reflection time-of-flight mass separator/spectrometer

Pauline Ascher1, Dinko Atanasov1, Dietrich Beck2, Klaus Blaum1, Christine Böhm1, Christopher Borgmann1, Martin Breitenfeldt3, R. Burcu Cakirli1, Thomas E. Cocolios4, Sergey Eliseev1, Sebastian George5, Frank Herfurth2, Alexander Herlert6, Magdalena Kowalska4, Susanne Kreim1,4, Jan Kurcewicz4, Yuri A. Litvinov2, David Lunney7, Vladimir Manea7, Enrique Minaya Ramirez2, Sarah Naimi1, Dennis Neidherr2, Marco Rosenbusch5, Stefan Schwarz8, Lutz Schweikhard5, Juliane Stanja9, Frank Wienholtz5, Robert N. Wolf5, Kai Zuber9

1Max-Planck-Institut für Kernphysik, Heidelberg, Germany 2GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany 3Instituut voor Kern- en Stralingsfysica, Leuven, Belgium 4CERN, Geneva, Switzerland 5Ernst-Moritz-Arndt-Universität, Greifswald, Germany 6FAIR GmbH, Darmstadt, Germany 7CSNSM-IN2P3-CNRS, Université de Paris Sud, Orsay, France 8NSCL, Michigan State University, East Lansing, USA 9Technical University Dresden, Dresden, Germany E-mail: [email protected]

State-of-the-art precision measurements have already been performed on many radioactive ions with the Penning-trap mass spectrometer ISOLTRAP [1] at ISOLDE/CERN. However, for the study of more and more exotic atomic nuclei, minute production rates often accompanied by huge isobaric background or half-lives down to milliseconds pose enormous challenges that require new experimental techniques. Thus, the ISOLTRAP setup has recently been enhanced with an electrostatic ion-beam trap acting as a multi-reflection time-of-flight mass separator/spectrometer (MR-ToF MS) [2-4]. It can be used for beam purification as exemplified in the case of the Penning-trap mass measurement of 82Zn [5]. In addition, it can act itself as a mass spectrometer either for an analysis of the ion beam provided by the ISOLDE facility [4] or for precision mass spectrometry of short-lived nuclides that are out of reach of the Penning trap, as shown recently in the case of neutron-rich calcium isotopes [5].

References

[1] M. Mukherjee et al., Eur. Phys. J. A 35, 1 (2008) [2] R.N. Wolf et al., Hyperfine Int. 199, 114 (2011); R.N. Wolf et al., Int. J. Mass Spectrom. 313, 8 (2012); R.N. Wolf et al., Nucl. Instrum. Meth. A 686, 82 (2012) [3] R.N. Wolf et al., Phys. Rev. Lett., 110, 041101 (2013) [4] R.N. Wolf et al., Int. J. Mass Spectrom. (2013) doi: 10.1016/j.ijms.2013.03.020; S. Kreim, EMIS proceeding, submitted (2013) [5] F. Wienholtz, accepted for publication (2013)

23 ESD 2013 Invited Talk No 8 I 8

Studies of molecular reaction dynamics using a cryogenic electrostatic ion beam trap

Robert E. Continetti

Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, San Diego CA 92093-0340 USA

E-mail: [email protected]

The use of a cryogenically cooled electrostatic ion beam trap to carry out studies of the reaction dynamics of energy-selected neutral reactive intermediates produced by photodetachment of negative ions will be reviewed. Taking advantage of the field-free region in the center of the Zajfman-style beam trap, we have measured photoelectron energy and angular distributions and carried out, in coincidence on an event-by-event basis, measurements of the neutral photofragment recoil to completely kinematically characterize dissociative photodetachment processes. Using these experimental techniques we have characterized experimentally the barrier to tunneling of the combustion intermediate HOCO to yield H + CO2 products and studied the transition state dynamics for the reaction F + H2O → HF + OH using the F¯(H2O) anion as a precursor. This work was supported by the U.S. Department of Energy under grant DE- FG03-98ER14879.

24 ESD 2013 Invited Talk No 9 I 9

Ion beam spectroscopy of DNA strands

L.M. Nielsen1 and S. Brøndsted Nielsen1

1 Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark

E-mail: [email protected].

Electronic coupling between photo-excited bases in nucleic acids is a topic of high current interest since it is of importance in photobiology for self-protection against solar UV light and for the employment of DNA strands as conductors in nanotechnology. For single bases the photophysics is well established. After photoexcitation the internal conversion back to the electronic groundstate proceeds via conical intersections in an ultrafast process (hundreds of femtoseconds). Hereafter the excess energy is distributed to the surrounding water in picoseconds[1]. This scheme protects the molecules, while in vacuum they are photodestroyed on the microsecond time scale. For longer strands and "real" DNA the situation is more complicated and less understood. Here two stacked bases are separated by 3.4 Å, and the π-electrons are close enough in space to couple, which alters their photophysics compared to the single bases. The coupling gives rise to new quantum states as linear combinations of single-base wavefunctions; they are denoted Frenkel excitons and represent collective excitation of more bases. The spatial extent of the excitons is hotly debated. The extent is relevant for DNA photoprotection but also for the ability of DNA strands to conduct current as the strength of π-stacks and the presence of delocalized domains determine the efficiency of electron hopping over long distances. The absorption spectra of DNA strands resemble those of single bases with no splitting of the band located at around 260 nm. Recent nontrivial calculations by Markovitsi and coworkers[2] on model strands indicated that the change in absorption induced by excitation to exciton states is to the blue as upper eigenstates carry high oscillator strengths but that the shift is small. In this talk I present action spectra recorded at the electrostatic ion storage ring in Aarhus (ELISA) of short singly - - - negatively charged strands of adenine bases, (dA)2 , (dA)3 , and (dA)4 . A comparison with the spectrum of dAMP- published by Weber and coworkers[3] show that the base- stacking interactions cause a small blueshift in agreement with the theoretical predictions. From the action spectra it is also established that internal conversion can compete with electron detachment when the excitation energy is above the detachment energy. Future developments will be discussed.

References [1] C.T. Middleton, K.D.L: Harpe, C. Su, Y.K. Law, C.E. Crespo-Hernández, and B. Kohler, Annu. Rev. Phys. Chem., 60, 217 (2009).

[2] B. Bouvier, J.-P. Dognon, R. Lavery, D. Markovitsi, P. Millié, D. Onidas, and K. Zakrzewska, J. Phys. Chem. B., 107, 13512 (2003). [3] J. C. Marcum, A. Halevi, and J. M. Weber, Phys. Chem. Chem. Phys., 11, 1740 (2009) [4] L.M. Nielsen, S.Ø. Pedersen, M-B.S. Kirketerp and S. Brøndsted Nielsen, J. Chem Phys., 136, 064302 (2012).

25 ESD 2013 Invited Talk No 10 I 10

Study on carbon cluster and polyyne anions in TMU E-ring

H. Shiromaru

Dept. Chem. Tokyo Metropolitan Univ. 1-1 Minami-Osawa, Hachioji 192-0397, Japan

E-mail: [email protected]

The chain-form carbon clusters show a well-known periodicity in the electronic structures; the ground states of even-numbered clusters are triplet, with the exception of C2, while those of odd-numbered ones are singlet. This is the origin of an even/odd alternation observed in abundance, reactivity, and so on, both for neutral and ionic carbon clusters. The alternation reported for delayed electron detachment of anions is one of such examples. When chain-form carbon anions were stored in the magnetic ring, millisecond timescale auto-detachment was observed only for odd-numbered - clusters except for C2 [1]. This is most likely the outcome of the even/odd alternation in the radiative cooling scheme. When an H atom is attached to one of the end carbons of an even-numbered carbon cluster, it will induce considerable change in the electronic structure. The even- numbered carbon clusters are highly cumulenic formally written as (C=C)n, while chemical bonding nature of H-capped cluster is H-(CC)n. In other words, the attached - H atom changes the cumulene into the polyyne. As for the anionic species, C2nH is the isoelectronic species of the stable HC2nH giving rise to the closed shell electronic - structure, and attracts wide interest in cosmochemistry. C6H is the first molecular anion - discovered in the interstellar space [2]. It was followed by successive finding of C2nH family implying that such anionic polyynes, together with the carbon cluster anions, may play an important role in the molecular evolution in a carbon-rich environment. The major formation channel is considered to be a two-body collision of the neutral and e-, and the evaluation of the radiative cooling rate of highly excited anions is indispensable for understanding of the anion abundance in space. - - - We will show the contrasting radiative cooling schemes of C5 , C6 , and C6H , which are the representatives of the odd-numbered, the even-numbered carbon cluster anions, and the polyyne anions, respectively. The experiments were performed using an electrostatic ion storage ring at Tokyo Metropolitan University (TMU E-ring) [3]. Hot anions were stored in the ring where they were gradually cooled by emitting IR or visible photons. After a specific storage time, the anions were reheated by a pulsed laser resulting in electron emission. The neutral particles generated by delayed detachment, at least after 17 s survival as the anion, were selectively detected. The total yield and the decay profiles as a function of time after reheating were analyzed in detail, for various - - storage times and excitation energies. The radiative cooling of C5 and C6H is - reasonably explained by the vibrational radiative cooling, whereas that of C6 needs significant contribution of recurrent fluorescence, as the case of PAH anions [4].

References [1] J. U. Andersen et al., Z. Phys D 40, 365-370 (1997). [2] M. C. McCarthy et al., Astrophys. J. 652, L141-L144 (2006). [3] S. Jinno et al., Nucl. Instrum. Methods Phys. Res. A 532, 477-482 (2004). [4] S. Martin et al., Phys. Rev. Lett. 110, 063003 (2013).

26 ESD 2013 Invited Talk No 11 I 11

Upper atmospheric Ions and Ion processes – Implications for trace gases and aerosol

Frank Arnold

Max-Planck-Institut für Kernphysik, Heidelberg, Germany

E-mail: :[email protected]

Upper atmospheric ions and ion processes are of interest for several reasons. They influence atmospheric electrical properties, potentially influence aerosol formation, and serve as powerful diagnostic tools in trace gas and aerosol detection. It has been hypothesized that atmospheric ions may even influence clouds and climate. Currently this, so called Ion-Cloud-Climate Connection is subject of a highly controversial discussion. Airborne ion mass spectrometry measurements, made on rockets, stratospheric balloons, and research aircraft have a major role in exploring atmospheric ions and ion processes. This contribution reviews major progress in our understanding of atmospheric ions and attempts to identify future developments. Regarding experiments, the focus is on airborne ion mass spectrometry, particularly made on rockets. Regarding major atmospheric implications, emphasis is placed upon the role of ion measurements in understanding mesospheric aerosol, molecular clusters, ultra trace gases, and clouds. Emphasis is also placed upon cosmic influences on mesosopheric ions, aerosol, and clouds. These cosmic influences include cosmic dust and energetic particle radiation.

27 ESD 2013 Invited Talk No 12 I 12

Ion-neutral merged beams experiments of astrophysical interest

X. Urbain1, A. O’Connor2, J. Stützel2, N. de Ruette2, K. A. Miller2, and D. Savin2

1 Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Belgium 2 Columbia Astrophysics Laboratory, Columbia University, New York, NY, USA

E-mail: [email protected]

Ion-molecule reactions play a key role in the chemistry of cold and diffuse environments, due to the long range polarization potential that efficiently brings together the colliding partners. In the gas phase, large molecules are built through successive additions of atoms and molecules resulting from binary encounters. Molecular ions have their share in this chemical network, and their reactivity with atomic species is still poorly understood especially in the temperature ranges of astrophysical relevance.

The merged beam configuration, where (re)circulating ions meet fast atoms travelling at equal speed along the same direction, has the potential to generate state-specific cross sections for most reactive processes, from charge transfer to chemical rearrangement. Single pass experiments have been conducted in the past [1], where atoms were produced from cations through charge exchange with a gaseous target, and molecular ions were obtained by electron impact ionization. Both techniques suffer from insufficient characterization of the internal energy. The atomic beam may also be produced in its ground state or term via photodetachment of the corresponding anion, as successfully demonstrated by Havener et al at ORNL [2] and Savin et al at Columbia [3]. This selection has proven essential for benchmark measurements. We will report on its first implementation for reactive scattering studies, in which a ground term carbon + beam was merged with an H3 beam, and show that some dynamical insight may be gained with excited reactants.

Both the CSR and DESIREE storage rings are nearing completion and commissioning, and will provide the necessary environment for internal relaxation of molecular species, and the appropriate geometry for low center-of-mass collisions with co-moving atoms and anions. We will review the foreseen hurdles along the path towards low- temperature chemistry with merged beams, and point to the new avenues these cryogenic machines will open in a not too distant future.

References [1] D. J. McClure, C. H. Douglass, and W. R. Gentry, J. Chem. Phys. 67, 2362 (1977). [2] C. C. Havener, M. S. Huq, H. F. Krause, P. A. Schulz, and R. A. Phaneuf, Phys. Rev. A, 39, 1725 (1989). [3] H. Kreckel, H. Bruhns, M. Čížek, S. C. O. Glover, K. A. Miller, X. Urbain, D. W. Savin, Science, 329, 69-71 (2010).

28 ESD 2013 Invited Talk No 13 I 13

Development of a cryogenic electrostatic ring in RIKEN

Y. Enomoto1, T. Masunaga1, Y. Nakano1 and T. Azuma1,2

1 AMO Physics Lab., RIKEN, Saitama, Japan 2 Dept. of Physics, Tokyo Metropolitan University, Tokyo, Japan E-mail:[email protected]

We have developed a cryogenic electrostatic ion storage ring, to explore especially the cooling process and collision dynamics of the cold molecular ions in the specific vibrational and rotational state. Figure 1 shows a cross sectional view of the storage ring. Electrodes are placed on a single base plate made of Chromium Copper (CrCu) alloy and this structure makes it easy to align each electrode precisely. The plate and electrodes are covered by a half- cylindrical shaped stainless steel rid attached to oxygen-free copper strips for cooling and we call this structure an inner vacuum chamber (IVC). The IVC is covered by a radiation shield made of aluminium plates and an outer vacuum chamber (OVC) for thermal isolation. We adopted completely LHe-free system, namely the IVC and the radiation shield is cooled by three GM cryocoolers whose cooling capacity is 3 W at 4.2 K in total. We have already finished assembly work and tested performance in vacuum and cooling. The temperature of the IVC is bellow 5 K after 150 hours of cooling. The pressure of the pumping station attached to the IVC is in the order of 10-11 Torr. Considering the pumping speed of the cryogenic chamber wall and conductance between cryogenic and room temperature sections, the pressure in the IVC is expected to be better than 10-14 Torr. Presently, an ECR ion source with a transport beamline is connected to the ring and the commissioning work is in progress.

Fig. 1. A cross sectional view of the cryogenic electrostatic ion storage ring at RIKEN

29 ESD 2013 Invited Talk No 14 I 14

First results from the Double ElectroStatic Ion-Ring ExpEriment, DESIREE

M. Gatchell1, H. T. Schmidt1, J. D. Alexander1, G. Andler1, M. Björkhage1, M. Blom1, L. Brännholm1, E. Bäckström1, T. Chen1, W. Geppert1, P. Halldén1, D. Hanstorp2, F. Hellberg1, A. Källberg1, M. Larsson1, S. Leontein1, L. Liljeby1, P. Löfgren1, S. Mannervik1, A. Paál1, P. Reinhed1, K-G. Rensfelt1, S. Rosén1, F. Seitz1, A. Simonsson1, M. H. Stockett1, R. D. Thomas1, H. Zettergren1 and H. Cederquist1

1 Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm, Sweden 2 Department of Physics, University of Gothenburg, SE-412 96 Gothenburg, Sweden

E-mail: [email protected]

Construction of the Double ElectroStatic Ion-Ring Experiment (DESIREE) [1,2] at Stockholm University has reached completion and the experiment is in the commissioning phase. DESIREE is a novel experiment where two cryogenically cooled electrostatic ion storage rings, each with a 8.6 m circumference, are enclosed in a single cryogenic vacuum chamber and share a common straight interaction section where oppositely charged ions may interact at meV level center-of-mass energies.

The experiment is at operational conditions with an inner chamber temperature of 13 K and pressure below 10-13 mbar. The first of the two rings is fully operational and its characteristics have been studied through the storage of 10 keV beams of carbon anions - - - - (C , C2 , C3 and C4 ) and their neutralization through interactions with background rest - gas. We are able store a C2 beam containing millions of ions. After an initial non- exponential decay due to the effects of space charge, the decay approaches a single exponential behavior with a lifetime of 7.5 minutes (figure 1).

Following the commissioning of the now operational second ring, this unique experiment will enable the study of mutual neutralization of pairs of cooled ions and the measurements of reaction kinetics through the use of a position sensitive multi-hit detector. Thus the study of gas phase ionic chemistry, such as that occurring in the interstellar medium, is possible. Figure 1: Signal from single ring storage of an initial 5 - Further commissioning results will be injection of 5×10 10 keV C2 ions. The ions are being presented at the conference. neutralized in collisions with rest gas with a 1/e lifetime of 7.5 minutes.

References [1] R. D. Thomas et al, Rev. Sci. Instrum. 82, 065112 (2011) [2] H. T. Schmidt et al, Int. J. Astrobiol. 7, 205 (2008)

30 ESD 2013 Invited Talk No 15 I 15

Status of the Cryogenic Storage Ring CSR

R. von Hahn1, A. Becker1, F. Berg1, K. Blaum1, F. Fellenberger1, M. Froese1, S. George1, F. Grussie1, M. Grieser1, D. Kaiser, C. Krantz1, H. Kreckel1, M. Lange1, S. Menk1, R. Repnow1, K. Spruck2, S. Vogel1, A. Wolf1

1Max Planck Institut für Kernphysik, Heidelberg, 69029 Germany 2Institut für Atom- und Molekülphysik, Justus-Liebig-Universität, Giessen, 35392, Germany

Email: [email protected]

The cryogenic electrostatic ion storage ring (CSR) [1] is approaching completion at the Max Planck Institute for Nuclear Physics in Heidelberg. Relatively low ion energies of 20 to 300 keV per charge state demand extremely high vacuum (p < 10 -13 mbar RTE, i.e., equivalent gas density at room temperature) to allow research on atomic, molecular and cluster ions. This also profits from the ultra-low black-body radiation level. Using a helium refrigerator system, the walls of the vacuum system seen by the particles will be cooled down to about 10 K, sufficient to prepare clusters and molecules in or near their rovibrational ground states. At dedicated positions, 2 K will be achieved for efficient pumping by cryocondensation of hydrogen. The cryogenic principles and vacuum concepts were tested at the cryogenic test facility (CTF) constructed for this purpose. A vacuum pressure of 8×10-14 mbar (equivalent gas density at room temperature) was verified allowing us to proceed within the proposed design principles for the CSR. Consisting of three experimental straight sections and one straight section for beam diagnostics, the CSR has a quadratic shape with a circumference of ~35 m. The beam tube is housed in a large toroidal cryostat composed of rectangular boxes (cross section 1.1 m × 1.1 m) with a stainless steel frame and aluminum cover plates. Two radiation shields at 80 and 40 K isolate the inner vacuum chamber from thermal radiation. These inner vacuum chambers are made from stainless steel wrapped in copper sheets for improved thermal conductance. They are connected via pure-copper strips to heat sinks at special pumping units, which offer large surfaces at 2 K for cryocondensation. The assembly of the first quadrant of the CSR has been completed. The section has been cooled down for test purposes, using laser tracking to measure the displacement and tilt of the electrostatic elements in the cryogenic chambers due to thermal shrinking. Deviations of <0.1 mm, well within the requirements, were confirmed. The temperatures of the chambers were measured to <10 K and at the pumping units (5 per quadrant) 2 K temperatures were achieved. Cryogenic cool-down times were 2 weeks, with the electrostatic elements (thermally anchored via the high voltage cabling) lagging 2 days behind in thermalizing. A large part of the structures around the ring are installed; beam diagnostic units for electric pickup signals and spatial profiles, detectors for neutral and charged fragments from interactions with the stored ions, the injection beam line, and an electron cooling device are under construction. A large electrostatic platform (300 kV) has produced first ion beams and will offer a versatile ion source area for supplying CSR ion beams. The talk gives an overview about motivation, technical concepts and the current realization status of the CSR.

References [1] R. von Hahn et al., Nucl. Instrum. Meth, Phys. Res. B 269, 2871-2874 (2011).

31 ESD 2013 Invited Talk No 16 I 16

Mass Spectrometry as Indispensible Tool to Investigate Catalytic Reactions

O. Trapp

Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany

E-mail: [email protected]

Mass spectrometry is one of the most important analytical tools to characterize and identify minute amounts of molecules in complex mixtures and is a very sensitive detector in separation sciences. Searching for highly efficient and (enantio-) selective catalysts is of great importance to develop benign chemical processes for industrial applications. The prerequisite for a directed design of catalysts is the understanding of how the kinetics, i.e. the activation barrier, in the mechanism are controlled by structural parameters. To understand a catalyzed reaction on a molecular level rate- controlling elementary steps need to be identified and comprehensive experimental kinetic data of a broad variety of substrates and intermediates, which are identified by mass spectrometry, need to be acquired.

The combination of separation selectivity and catalytic activity in a single setup in combination with mass spectrometric detection allows performing high-throughput kinetic analysis of catalyzed reactions [1,2]. In contrast to commonly used (micro) reactors, where the reaction, separation and quantification of conversion are consecutively performed and therefore the throughput is limited to the study of single reactions, several reactions can be simultaneously investigated by injection of a substrate library. Multiple reaction monitoring mass spectrometry is used to simultaneously detect several processes and to distinguish reaction path ways [3]. Results for the screening of (enantioselective) hydrogenation catalysts, C-C-cross coupling catalysts [4], enantioselective rearrangements, metathesis catalysts [5], higher order reactions and strategies to elucidate reaction mechanisms [6,7] and to determine reaction rate constants will be shown.

References [1] O. Trapp, S.K. Weber, S. Bauch, W. Hofstadt. Angew. Chem. Int. Ed. 46, 7307-7310 (2007). [2] O. Trapp, S.K. Weber, S. Bauch, T. Bäcker, W. Hofstadt, B. Spliethoff. Chem. Eur. J. 14, 4657-4666 (2008). [3] O. Trapp. J. Chromatogr. A 1217, 1010-1016 (2010). [4] S.K. Weber, S. Bremer, O. Trapp. Chem. Eng. Sci. 65, 2410-2416 (2010). [5] C. Lang, U. Gärtner, O. Trapp. Chem. Commun. 47, 391-393 (2011). [6] M.J. Spallek, S. Stockinger, R. Goddard, O. Trapp. Adv. Synth. Catal. 354, 1466-1480 (2012). [7] M. Kamuf, F. Rominger, O. Trapp. Eur. J. Org. Chem. 4733-4739 (2012).

32 ESD 2013 Invited Talk No 17 I 17

Micro-calorimetric detectors for fast molecules and fragments

A. Fleischmann1, L. Gamer1, C. Pies1, A. Pabinger1, C. Enss1, O. Novotný2,3, D.W. Savin3, C. Krantz2, A. Wolf2

1 Kirchhoff Institute for Physics, Heidelberg University, INF 227, 69120 Heidelberg, Germany 2 Max-Planck-Institute für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany 3 Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA

E-mail: [email protected]

Moving dissociative recombination (DR) experiments on molecular ions and clusters and other types of ion fragmentation studies from magnetic storage rings to the new electrostatic Cryogenic Storage Ring (CSR) will allow new benchmark measurements as the reactions can start in the rotational ground state. At the same time, the electrostatic storage at significantly reduced energy will challenge the detection schemes and conventional detectors will often not be able to provide all necessary information. We are presently developing large area magnetic calorimeters for the position and energy resolved detection of massive particles, as required for the determination of the kinetic energy release, the branching ratios and the identification of the masses of the fragments in DR reactions. The metallic magnetic micro-calorimeters (MMC) developed by our group at KIP are operated at about 30 milli-Kelvin and use a paramagnetic sensor to monitor the temperature of a massive particle absorber. The absorption of a particle causes an increase of the detector temperature and a corresponding drop of sensor magnetization, which is detected by a low-noise high-bandwidth dc-SQUID magnetometer and serves as a measure of the deposited energy. The present detector arrays for high resolution x- ray spectroscopy consist of 250-m sized pixels with a quantum efficiency close to 100%, an energy resolution below 3 eV for x-ray energies up to 10 keV, and excellent linearity. The active area of our present detector prototype ‘PIZZA’ for the CSR has a diameter of 36 mm and is composed of 16 absorber segments to stop the molecular fragments. A paramagnetic temperature sensor is connected to each absorber along its arc. In this configuration the energy deposited by a molecular fragment and hence approximately its mass are proportional to the time integral of the detected temperature pulse, while its radial position can be derived from the signal risetime due to the finite diffusivity of heat inside the absorber segment. We present the physics of MMCs, design considerations and the micro-fabrication of present prototypes. We compare the performance as recently tested with light pulses from LEDs and 6 keV x-rays to the one expected from detailed numerical simulations, and discuss the potential degradation of energy resolution due to the creation of lattice defects when the detector is used for massive particles.

33 ESD 2013 Invited Talk No 18 I 18

Observation of Ultrafast Intra-Molecular Charge Migration in a Biomolecule

L. Belshaw1, F. Calegari2,3, M.J. Duffy1, A. Trabattoni2, L. Poletto3, M. Nisoli2, and J.B. Greenwood1. 1 Centre for Plasma Physics, Department of Physics and Astronomy, Queen’s University, Belfast 2 Politecnico di Milano, Department of Physics, CNR-IFN, Milan, Italy 3 Institute of Photonics and Nanotechnologies, CNR-IFN, Milan, Italy E-mail: [email protected], j.greenwood.ac.uk

Ultrafast charge migration within single molecules is the fundamental initiator of many important biological processes and chemical reactions, including photosynthesis, catalysis, and DNA damage by ionizing radiation [1,2]. Recent developments of attosecond science not only facilitate the observation of such dynamics, but also unveil the possibility of controlling electron dynamics within molecules and nanostructures. We present here the first experimental observation of ultrafast charge migration in a biological molecule - the amino acid phenylalanine. To facilitate gas-phase studies, we have developed a laser-induced acoustic desorption (LIAD) technique to produce clean, neutral plumes of isolated molecules [3]. This target was irradiated by an XUV pulse (consisting of two attosecond pulses separated by 1.5 fs) to ionise an electron from the molecule, creating a positive hole. By using a 6 fs, visible/near-infrared probe pulse at a controllable delay time, the positive charge was observed to migrate to one end of the cation within 30 fs [4]. This was achieved by observing the yield of a doubly charged ion which was sensitive to the relative location of the hole (figure 1). A process on this timescale is consistent with a model of ultrafast, coherent, charge oscillations to and from one end of the cation being terminated due to nuclear rearrangement. This scheme provides an extremely powerful technique for further studies of this phenomenon, in which we can hope to understand more fully the principles of ultrafast intra-molecular charge migration.

Figure 2: The yield of doubly charged immonium ions with respect to the time delay between the XUV pump and VIS/NIR probe. Charge migration to one end of the cation suppresses ionisation by the probe.

References [1] O. Bixner et al., J. Chem. Phys. 136, 204503 (2012). [2] B. Giese, M. Graber, and M. Cordes, Curr. Opin. Chem. Biol. 12, 755 (2008). [3] C.R. Calvert et al., Phys. Chem. Chem. Phys. 14, 6289 (2012). [4] L. Belshaw, F. Calegari, M.J. Duffy, A. Trabattoni, L. Poletto, M. Nisoli, and J. B. Greenwood, J. Phys. Chem. Lett. 3, 3751 (2012).

34 ESD 2013 Invited Talk No 19 I 19

Ion beam interactions with ultra-short laser pulses

Robert Moshammer

Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg E-mail: [email protected]

The prospects of using state-prepared atomic or molecular ions circulating in the CSR as a target for experiments with intense, ultra-short laser pulses will be discussed. This way, and in combination with the new CSR in-ring Reaction Microscope for electron and ion spectroscopy, a large variety of topics can be studied under unprecedented clean conditions, ranging from spectroscopy of stored atomic or molecular species to time- resolved observations of photon-induced molecular processes on time scales from pico- to femtoseconds. The photo-ionization dynamics of atomic, molecular or cluster ions will become accessible as well as reactions involving isomerization or nuclear rearrangements in excited molecules. Moreover, by means of pump-probe experiments with fs laser-pulses it is anticipated that fundamental molecular reactions (rotational, vibrational or electronic excitations) can be observed in real time starting from ground- state or even laser-excited, state-prepared ions stored in the CSR.

Figure: Sketch of the experimental setup for photoelectron spectroscopy of stored ions.

35 ESD 2013 Invited Talk No 20 I 20

Laser photofragmentation and ultrafast time-resolved dynamics of trapped complex molecular ions

C. Riehn, Y. Nosenko, D. Imanbaew, S. Kruppa, C. Kerner, W. R. Thiel

Department of Chemistry, TU Kaiserslautern, Erwin-Schrödinger-Str., 67663 Kaiserslautern, Germany

E-mail:[email protected].

Elementary processes, like electronic coupling, energy and charge transfer and fragmentation dynamics of mass-selected, isolated ionic molecular species are studied at a 50 fs-100 ps time scale. This project is part of the collaborative research center SFB/TRR 88 (3MET), focusing on cooperative effects in homo- and heterometallic complexes. [1] The ultrafast time-resolved measurements are based on pump-probe transient photofragmentation. After photoexcitation by a resonant pump laser pulse via an electronic transition the subsequent dynamics are probed by a variably time-delayed second laser pulse which produces an electronic-state-specific fragmentation pattern. [2] The newly designed experimental setup consists of a kHz 50fs-amplified Ti:Sa-laser system equipped with two optical parametrical generator/amplifier units for independent wavelength tuning (240-2600 nm) of pump and probe pulses and an electrospray ion trap mass spectrometer for ion selection, storage and mass analysis (up to 3000 m/z). The multiphoton ionization of neutral furan (C4H4O) inside the trap was employed for

cross-correlation measurement (~120fs). 2- Photofragments of [Pt2(Ag)-complex] We present laser photo- yield fragmentation and time-resolved measurements on a dianionic Pyrophosphito-diplatinum- 2- complex [Pt2(P2O5H2)4H2] and its silver-containing derivative 2- m/z [Pt2(P2O5H2)4AgH] . Ultrafast electronic gas phase dynamics is observed via the parallel channels of electron detachment and fragmentation.

The excited state dynamics (~ 2ps) of a set of newly Fs-photofragmentation synthesized ruthenium-(II) transfer hydrogenation catalysts of [Ru(II)-catalyst]+ [(η6-cymene)RuCl(apypm)]+(apypm=2-R-4-(pyridinyl)- pyrimidine, R=NH2/N(CH3)2) were investigated in the gas phase by transient photofragmentation, revealing the same species as considered crucial for its activity in solution. [3] -1000 0 1000 2000 3000 pump-probe delay / fs References [1] http://www.uni-kl.de/3met [2] D. Nölting, T. Schultz, I.V. Hertel, R. Weinkauf, Phys. Chem. Chem. Phys. 8, 5247- 5254 (2006). [3] L. T. Ghoochany, S. Farsadpour, F. Menges, Y. Sun, G. Niedner-Schatteburg, W.R. Thiel, Chem. Eur. J. (submitted, 2013).

36 ESD 2013 Invited Talk No 21 I 21

Status at Mini-Ring: recent progress and perspectives

R. Brédy1, M. Ji1, C. Ortéga1, J. Bernard1, G. Montagne1, A. Cassimi2, C. Joblin3, L. Chen1 and S. Martin1

1 Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex, France 2 CIMAP, GANIL Université de CAEN, Bd. H. Becquerel, Caen, France 3 Université de Toulouse, UPS-OMP, IRAP, Toulouse, France

E-mail: [email protected]

Mini-Ring is a compact electrostatic storage ring composed of two electrostatic conical mirrors and four pairs of deflector plates [1]. The latest developments include the upgrade of the acquisition system with a position sensitive detector (PSD) to record the arrival time and position of the neutrals exiting the ring along one of the straight line. This upgrade, combined with the recording of 12 keV Ar+ beam trajectory with a CCD camera placed in front of the window at the top of the experiment (Figure 1) allowed us to reduce the Betatron oscillation and improve the accuracy of the lifetime + measurement. Intense beams of molecular PAH cations and dications, C60 , have been produced using a 10 Ghz ECR ion source with very low HF power (less than 0.5 W). The time evolution of the internal energy distribution of the stored ions was probed using laser induced dissociation at different storage time and cooling rates of the Anthracene cation have been measured at different internal energies [2]. Measurements of kinetic energy release KER using the PSD will also be presented.

. Figure 3. Photo of Mini-Ring. The light emitted along the Ar+ beam trajectory is due to collisions with nitrogen gas injected into the vacuum chamber at pressure of about 10-4 mbar. The blue light is due to the excitation of the N2 molecules. The MCP imaging detector is placed at the bottom left. A small spot due to neutralized Ar is well observed on the MCP.

References [1] J. Bernard et al. 2008 Rev. Sci. Instrum. 79 075109 (2008) [2] S. Martin et al. 2008 Phys. Rev. Lett. 110 063003 (2013)

37 ESD 2013 Invited Talk No 22 I 22

The new electrostatic storage ring SAPHIRA

H. B. Pedersen1, H. Bechtold1, L. S. Harbo1, H. V. Kiefer1, H. Kjeldsen2, L. Lammich1, A. Svendsen1, E. Søndergaard1, Y. Toker1, and L. H. Andersen1

1 Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark 2Centre for Storage Ring Facilities, Aarhus University DK-8000 Aarhus C, Denmark

E-mail: [email protected].

A new electrostatic Storage ring in Aarhus for PHoton Ion Reaction Analysis (SAPHIRA) has recently been designed, set up, and commissioned at Aarhus University. SAPHIRA is constructed in a square geometry (1 m x 1 m) and features a compact ion optical design with four modular corners and four straight sections where the stored ion beam is accessible for instance for interaction with photon pulses in both merged and crossed beam geometries. The straight sections are easily exchangeable without change to the ion optical lattice, which provide high flexibility for experiments - with a stored ion beam. SAPHIRA was commissioned using a 5 keV ion beam of NO2 extracted from a hollow cathode discharge in a home build ion source and guided into the storage ring with the electrodes of one corner biased to zero potential. Ion trapping was obtained by fast switching the electrodes of this corner to a high potential. The subsequent decay rate of stored ions as observed by a monitoring neutral fragments (N, O, and NO2) exiting through a corner of the ring is displayed in the figure. After a few milliseconds of trapping, an exponential decay with a lifetime of ~45 ms was seen with a residual gas pressure of 10-8 mbar in the ring.

SAPHIRA is a prototype for a second storage ring that will be part of an endstation at the upcoming ASTRID2 synchrotron radiation facility [1] dedicated to studies of photon induced processes in atomic and molecular ions. Another central part of this endstation is a newly realized Radio-Frequency (RF) ring electrode ion trap combined a Quadrupole Mass Spectrometer (QMS) on a high voltage platform in a ultra high vaccum environment, where trapped ions can be irradiated with high energy radiation from ASTRID2 or with laser light along the trap axis. The realization of a scheme for injecting ions from an initially fast moving beam into the RF trap without the use of buffer gas [2] has been developed and first results of experiments that demonstrate of the full functionality of this combined RF-QMS system has recently been obtained.

References [1] http://www.isa.au.dk/facilities/astrid2/astrid2.asp [2] A. Svendsen et al., Phys. Rev. A.87, 043410 (2013).

38 ESD 2013 Invited Talk No 23 I 23

Photodetachment spectroscopy of trapped anions

R. Wester1

1 Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria

E-mail: [email protected]

Photodetachment of negative ions is an important process for the destruction of interstellar molecular anions by light emitted from stars. Using a 22-pole radiofrequency ion trap [1,2] we have developed a photodetachment tomography scheme to precisely measure absolute cross sections for atomic and molecular anion photodetachment [3,4]. - We have applied this scheme to several interstellar negative ions in particular C4H and - - - C6H [5] as well as CN and C3N . Negative ion photodetachment tomography also turned out to be a versatile tool to investigate the effective potential of radiofrequency ion traps [6] and to measure the internal excitation of trapped molecular and cluster anions [7]. In addition, we have recently employed this to investigate the interaction of trapped OH- anions with ultracold rubidium atoms [8].

References

[1] D. Gerlich, Physica Scripta T59, 256 (1995) [2] R. Wester, J. Phys. B 42, 154001 (2009) [3] S. Trippel, J. Mikosch, R. Berhane, R. Otto, M. Weidemüller, R. Wester, Phys. Rev. Lett. 97, 193003 (2006) [4] P. Hlavenka, R. Otto, S. Trippel, J. Mikosch, M. Weidemüller and R. Wester, J. Chem. Phys. 130, 061105 (2009) [5] T. Best, R. Otto, S. Trippel, P. Hlavenka, A. von Zastrow, S. Eisenbach, S. Jezouin, R. Wester, E. Vigren, M. Hamberg, W. D. Geppert, Ap. J. 742, 63 (2011) [6] R. Otto P. Hlavenka, S. Trippel, J. Mikosch, K. Singer, M. Weidemüller, R. Wester, J. Phys. B 42, 154007 (2009) [7] R. Otto, A. von Zastrow, T. Best, R. Wester, Phys. Chem. Chem. Phys. 15, 612 (2013) [8] J. Deiglmayr, A. Göritz, T. Best, M. Weidemüller, R. Wester, Phys. Rev. A 86, 043438 (2012)

39 ESD 2013 Invited Talk No 24 I 24

Perspectives for Investigations of Chiral Systems with Ion Beams

S. Schippers

Institut für Atom- und Molekülphysik, Justus-Liebig-Universität Gießen, Leihgesterner Weg 217, 35392 Gießen, Germany

E-mail: [email protected]

Electrons in chiral molecules move in left- or right-handed electromagnetic fields which are generated by the spatial arrangement of the nuclei. Chirality in the electron cloud is not only induced by the nuclear skeleton but also by interactions among the electrons and between electrons and individual nuclei. This kind of interaction is mediated by the weak force which is the only fundamental force in nature that is known to distinguish between left and right. Moreover, chirality can be induced in achiral systems by excitation with chiral projectiles such as circularly polarized electromagnetic radiation or spin polarized electrons. Both, the chirality that is induced by the electron-electron and electron-nucleus interactions and the chirality that is induced by chiral projectiles originate in the electronic system and may subsequently be transferred to the nuclear arrangement. The interplay between the chirality of the electron shell and the chirality of the nuclear arrangement in molecular systems has hitherto not been studied very intensely.

Recently, a newly formed collaboration comprising experimental and theoretical physicists and chemists from the Universities of Darmstadt, Frankfurt, Giessen and Kassel has received substantial funding from the German Federal State of Hesse for the investigation of the Electron Dynamics of CHiral systems. Spearheaded by the University of Kassel, the ELCH consortium [1] set out to perform detailed investigations of small chiral neutral and electrically charged molecules (e.g. CHBrClF) using different types of chiral probes i) synchrotron radiation, ii) high-power laser pulses, and iii) spin polarized particles (electrons).

In my talk I will introduce the scientific objectives of the ELCH collaboration and discuss selected future experiments such as dissociative recombination of chiral molecular ions with spin polarized electrons.

References

[1] http://www.uni-kassel.de/elch

40 ESD 2013 Invited Talk No 25 I 25

Molecular structure conversion of stored monoanions in electrostatic storage ring

T. Tanabe1,2, M. Saito3, K. Noda2 and E. B. Starikov4

1 High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan 2 National Institute of Radiological Sciences, Anagawa, Chiba 263-8555, Japan 3 Kyoto Prefectural University, Kyoto 606-8522, Japan 4 Chalmers University of Technology, Gothenburg 412 96, Sweden

E-mail: [email protected]

Photodissociation was studied using an electrostatic storage ring (Fig. 1) for fluorescein and its 5-carboxyfluorescein analogue monoanions (Fig. 2) [1]. Ions were produced by an electrospray ion source and stored in an ion trap. They were subsequently injected into the ring after their acceleration to 20 keV. The stored ions were irradiated by an OPO laser (wavelength: 410–650 nm) and neutral products were detected. The storage time was variable up to the order of seconds. The photodissociation neutral spectra as a function of time vary depending on the storage time (Fig. 3) as well as the laser wavelength. By comparing the wavelength spectra of our study with absorption spectra reported recently, we deduced that the spectra originated from different tautomers (MAC and MAF in Fig. 2). Moreover, the wavelength spectra vary during long-term storage in the storage ring. The origin of this phenomenon is attributed to the interconversion of tautomers. Similar results were also observed for desodiated orange I monoanions ([M-Na]-, M: C16H11N2NaO4S), which also exhibit tautomerism (azo and hydrazone forms).

Fig. 1 Experimental setup.

Fig. 2 Chemical structures of Fig. 3 Time spectra for different fluorescein monoanions. storage times in the ring. References [1] T. Tanabe, M. Saito, K. Noda, E. B. Starikov, Eur. Phys. J. D 66, 163 (2012).

41 ESD 2013 Invited Talk No 26 I 26

Electron autodetachment of sulfur hexafluoride anions

S. Menk1, K. Blaum1, S. Das2, M. W. Froese1, M. Lange1, M. Mukherjee2, R. Repnow1, D. Schwalm1,3, R. von Hahn1, A. Wolf1

1 Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany 2 Centre for Quantum Technologies, National University Singapore, Singapore 117543 3 Weizmann Institute of Science, Rehovot 76100, Israel

E-mail: [email protected]

− Vibrational autodetachment (VAD) to SF6 [1] is energetically allowed for SF6 anions with a total excitation energy above the electron affinity (EA). The process was previously studied at ELISA (Aarhus) finding a power law decay [2]. Here we report − experimental studies on the process with rovibrationally hot SF6 anions produced in a cesium sputter ion source and trapped as a 6 keV ion beam in the <15 K cryogenic ion beam trap CTF [3] in Heidelberg. The device offers highest sensitivity to low intensities − of the SF6 neutralization signal and long undisturbed ion storage times (>800 s) for − 4 −3 stable SF6 ions. This is achieved by extremely low residual gas densities near 10 cm (few 10−12 mbar) in the trapping region, realized by cryogenic pumping of the residual − hydrogen. Neutralization of the excited SF6 anions due to VAD could be observed up to 100 ms after the ion production, covering almost five orders of magnitude in the intensity and dramatically improving on previous sensitivity [2]. The measured detachment rates reflect the vibronical coupling and the density of initial − SF6 excited states near the EA. Owing to the highly symmetrical geometric structure of - the system (octahedral for SF6, slightly distorted for SF6 [4]) the vibronical coupling was recently modeled in much detail [5]. The EA threshold itself is still controversial in a rather large interval around 1 eV [4-7] as a considerable theoretical challenge. At early decay times up to 10 ms we observe neutralization rates following a power law − in time and exhibiting sensitivity to the SF6 production environment in the ion source. For later times and at previously unobserved low rates, we find an even steeper decline of the signal and attribute it to the strongly decreasing autodetachment rates of the near- − threshold states in SF6 as well as to the depopulation of states by radiative stabilization. We developed a detailed model using detachment rates recently calculated by combining statistical rate theory with electron attachment data [3] and assuming a − thermalized initial rovibrational excitation of SF6 . Systematic variations of the measured decay curves with the ionic internal excitation (varied by changing ion source parameters) could be interpreted by this model and allow us to deduce the adiabatic − electron affinity of SF6 and the radiative stabilization rate of excited SF6 near its detachment threshold.

References [1] L. G. Christophorou, J. Phys. Chem. Ref. Data 29, 267 (2000). [2] J. Rajput et al., Phys. Rev. Lett. 100, 153001 (2008). [3] M. Lange et al., Rev. Sci. Inst. 81, 055105 (2010). [4] W. Eisfeld, J. Chem. Phys. 134, 129903 (2011); W. Eisfeld, J. Chem. Phys. 134, 054303 (2011). [5] J. Troe et al., J. Chem. Phys. 136, 121102 (2012). [6] A. Karton et al., J. Chem. Phys. 136, 197101 (2012). [7] J. C. Bopp et al., J. Phys. Chem. A 111, 1214 (2007).

42 ESD 2013 Invited Talk No 27 I 27

Orbitrap Mass Spectrometry

A. Makarov, D. Grinfeld

Thermo Fisher Scientific, Bremen, Germany

E-mail: [email protected]

In a special class of ion traps, referred as isochronous traps, the stored ions make oscillations with the frequency substantially independent of their orbital parameters. E.g. the ion cyclotron resonance (ICR) traps utilize the property of the Larmor precession frequency to be independent of the particle energy in the uniform magnetic field but the ion’ mass-to-charge ratio only, which allows most precise ion mass measurements. The use of superconductive magnets makes, however, the ICR mass spectrometers bulky and expensive. As a response to this challenge, pure electrostatic isochronous ion traps are to be adopted for the mass spectrometry applications.

It is well known that no stationary stable equilibrium exists in the electric field. Nevertheless, rotational ion motion can be effectively confined. The idea of orbital charged particle confinement dates back to 1923 when Kingdon proposed trapping the positive ions revolving around a negatively charged filament [1]. This approach was further developed by Knight [2] who proposed the quadro-logarithmic electrostatic field  r 2 r   2 2    C z   rm ln   2 rm  generated by a negatively charged wire and a pair of positively charged conical caps. The Knight’s trap offered enhanced ion lifetime, and it was first reported that the harmonic nature of the axial ion oscillations can be employed to separate the trapped ions according to their mass-to-charge ratios with the use of RF excitation technique.

Further advance was connected with drastic precision improvement of the quadro- logarithmic potential with the use of specially machined axisymmetric electrodes whose shapes follow desirable equipotential lines [3]. It allowed keeping the axial ion oscillations coherent during up to several seconds. The combination of induced-current detection and Fourier transform signal processing offered the opportunity to obtain precise mass spectra for any analyte ion mixture. Orbitrap(TM) is now a ‘heart’ of the whole family of mass-spectrometric equipment with up to one million resolving power.

Despite of the sub-micron manufacturing precision, the analytical orbital ion trap is to be thoroughly balanced to compensate for the residual field perturbations. Challenges of the fine aberration compensation are especially emphasized in our presentation along with consideration of fanciful space-charge effects.

References [1] K.H. Kingdon, Phys. Rev. 21, p. 408 – 418 (1923) [2] R.D. Knight, Appl. Phys. Lett. 38(4), p. 221-223 (1981) [3] A. Makarov, Anal. Chem., 72, p. 1156-1162 (2000)

43 ESD 2013 Invited Talk No 28 I 28

Energy transfer between ion clouds in multi-reflection ion traps

M. Rosenbusch, G. Marx, L. Schweikhard and R. N. Wolf

Institut für Physik, Ernst-Moritz-Arndt Universität Greifswald, 17489 Greifswald

E-mail: [email protected]

Electrostatic multi-reflection ion traps (MR-ITs) are a recent development for the storage of fast (i.e. keV) ion bunches [1,2]. They provide confinement for charged particles of defined kinetic energies, independent of their masses. In contrast to most ion storage rings, MR-ITs are only of table-top size while providing similar conditions for atomic-physics and mass-spectrometry applications. They consist of two electrostatic ion mirrors facing one another to reflect the particles back and forth between them. Axial and transversal confinement is achieved by optimized mirror potentials. An example of such a device is the multi-reflection time-of-flight mass separator (MR- ToF MS) at the ISOLTRAP mass spectrometer at ISOLDE/CERN. It provides a high mass resolving power R=m/∆m in excess of 105 for isobaric purification of radioactive ion beams in shortest time [3,4]. To advance the MR-IT as an efficient high-resolution mass separator, the number of ions to be injected per cycle has to be as high as possible. However, space-charge effects can hinder the separation of the different ion species [5] and the counterintuitive “self-bunching” effect [6] may lead to increased ion densities in spite of the repulsing Coulomb interactions. An MR-ToF MS has been set up at the University of Greifswald, which allows one to study these effects. Recent measurements show that when two isobaric ion species are stored simultaneously, they may experience significant changes in their axial kinetic energy, which depend on the number of trapped ions. The presentation will include these measurements as well as many-ion simulations with a modified particle-particle algorithm for the Coulomb interaction suited for graphics processing units [7].

References [1] H. Wollnik and M. Przewloka, Int. J. Mass Spectrom. Ion Process., 96, 267-274 (1990) [2] D. Zajfman et al., Phys. Rev. A, 55, R1577-1580 (1997) [3] R.N. Wolf et al., Phys. Rev. Lett., 110, 041101 (2013) [4] R.N. Wolf et al., Int. J. Mass Spectrom. accepted (2013) [5] M. Rosenbusch et. al., AIP Conf. Proc., 1521, 53-62 (2012) [6] D. Strasser et al., Phys. Rev. Lett., 89, 283204 (2002) [7] S. Van Gorp et al., Nucl. Instrum. Meth. A, 638, 192-200 (2011)

44 ESD 2013 Invited Talk No 29 I 29

Low center-of-mass energy collisions between Polycyclic Aromatic Hydrocarbon ions and noble gases

M. H. Stockett1, J. D. Alexander1, U. Bērziņš2, T. Chen1, K. Farid1, M. Gatchell1, A. Johansson1, K. Kulyk1, H. T. Schmidt1, H. Zettergren1 and H. Cederquist1

1 Department of Physics, Stockholm University, Stockholm, SE-106 91, Sweden 2 Institute of Atomic Physics and Spectroscopy, University of Latvia, Riga, LV-1586, Latvia

E-mail: [email protected]

Polycyclic Aromatic Hydrocarbons (PAHs) are an important component of interstellar dust and gas and are probably responsible for the ubiquitous infrared emission bands present in the spectra of many galactic and extragalactic sources [1]. The processes by which PAHs and other large molecules (e.g. fullerenes) are formed and destroyed, for example in collisions between PAHs and ions in interstellar shocks, in the interstellar medium are not yet understood. Experiments on collisions between PAH ions and atoms, particularly in the 100 eV energy regime, may elucidate the role of such collisions in the processing of interstellar carbon.

We will present the results of collision induced dissociation (CID) experiments between small (12 to 24 carbon atoms) PAH ions and rare gases conducted at center-of-mass energies (for helium) ECM = 110 eV. The results differ qualitatively from previous work, particularly in the CHx loss channel (marked * in the figures), which is much more prominent than is typically observed and here it even becomes dominant for the larger PAHs. In thermally driven processes such as photo-induced dissociation, evaporation of H-atoms and C2H2 units are typical results of the lowest energy decay pathways [2]. For the present collisions, fragmentation is initiated by prompt knock-outs of single carbon atoms, after which the excited fragment ion may decay further. Parallel theoretical work reveals that nuclear stopping is the main source of energy deposition in collisions with helium while electronic stopping becomes more significant for heavier target gases.

We find that the larger PAHs are less likely to decay further following single carbon knock-outs. These results have important implications for astrochemistry by suggesting efficient routes to highly reactive fragments with unsaturated carbon atoms. In contrast, photo-absorption favors more stable and less reactive fragmentation products.

References [1] A. G. G. M. Tielens, Annu. Rev Astron. Astrophysics 46, 289 (2008). [2] H. A. B. Johansson et al., J. Chem. Phys. 135, 084304 (2011).

45 ESD 2013 Invited Talk No 30 I 30

Isolated Transition Metal Clusters: Formation and Cold Ion Trap Investigation for their magnetic properties

M. Tombers1, J. Meyer1, H. Kampschulte1, S. Peredkov2, M. Neeb2, W. Eberhard3, G. Niedner-Schatteburg1

1 TU Kaiserslautern, Fachbereich Chemie, D-67663 Kaiserslautern, Germany 2 BESSY II, Helmholtz Zentrum Berlin Mat. & Energie, D-12489 Berlin, Germany 3TU Berlin, Inst. Opt. & Atomare Physik, D-10623 Berlin, Germany

E-mail: [email protected]

In order to determine the spin and orbit contributions to the magnetic moments of size selected transition metal clusters in the gas phase, we have defined a Penning cryo trap based experimental scheme in conjunction with a laser vaporization cluster ion source and with X-ray induced Magnetic Circular Dichroism (XMCD) measurements[1]. These measurements utilize brilliant, tunable and circularly polarized x-ray radiation as available at the BESSY II synchrotron facility. We have recorded data of size selected cationic cobalt[2], iron and nickel clusters (7 ≤ n ≤ 17). We compare our results to spin- and orbit data of atoms and of the bulk, and to the total magnetic moments of clusters investigated by Stern-Gerlach experiments.

References

[1] Peredkov, S.; Savci, A.; Peters, S.; Neeb, M.; Eberhardt, W.; Kampschulte, H.; Meyer, J.; Tombers, M.; Hofferberth, B.; Menges, F.; Niedner-Schatteburg, G. J. Electron Spectrosc. Relat. Phenom, 184, 113-118 (2011) [2] Peredkov, S.; Neeb, M.; Eberhardt, W.; Meyer, J.; Tombers, M.; Kampschulte, H.; Niedner- Schatteburg, G., Physical Review Letters, 107, 233401 (2011)

46 ESD 2013 Invited Talk No 31 I 31

Photo-induced non-adiabatic dynamics in biosystems: intrinsic dual photoresponse of anionic chromophores and selective tuning by proteins

A. V. Bochenkova1,2

1 Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark 2 Department of Chemistry, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia

E-mail: [email protected]

In contrast to the well-established paradigms in science that take for granted a decoupling of nuclear and electronic motions, our work aims at highlighting the importance and ubiquity of the non-adiabatic processes in nature, in which the electronic and nuclear dynamics are coupled with a remarkable efficiency. Such an electron-to-nuclei pairing is shown to be a key in understanding mechanisms by which the photoactive proteins tune the response of their light-absorbing molecular units and guide photochemical reactions that lie behind their functioning. By using state-of-the-art electronic structure theory combined with the experimental results obtained through a time-domain approach to action spectroscopy, we reveal a striking fundamental interplay between electronic and nuclear dynamics in competing excited-state decay channels of the deprotonated chromophore of the Green Fluorescent Protein (GFP). A non-adiabatic nature of the excited-state dynamics bridges the gap between their inherent timescales and unexpectedly results in co-existing mutual energy-borrowing mechanisms in the frame of a single molecular anion. We show that specific vibrational modes can facilitate fast energy exchange between nuclei and electrons on the (sub)picosecond timescale. The mode-specific non-adiabatic couplings result in either photoinduced vibrationally-mediated electron emission or electronic de-excitation through conical intersections. Remarkably, the relative efficiencies of these channels are wavelength dependent, since an emission-active vibrational mode is directly excited upon photoabsorption. We show that photodetachment proceeds via vibrational autodetachment out of the bound excited state al low energy, whereas electron ejection is facilitated by vibrational Feshbach resonances at higher energy. We underscore similarities anticipated in the excited-state behaviour of anionic tyrosine-based chromophores of various photoactive proteins, as well as compare the properties of the bare chromophore to those inside the protein. We show remarkable similarity of the early-time photo-induced nuclear dynamics in the gas phase and in the protein and emphasize the close interrelation between the excited-state dynamics and the corresponding spectral shapes. Finally, we discuss the ways, by which the GFP-like proteins may use the intrinsic dual electron-to-nuclei coupling to promote a selective photoresponse.

This work was granted access to the HPC resources of the Leibniz and RZG Supercomputing Centers (Garching, Germany) made available within the Distributed European Computing Initiative by the PRACE-2IP, receiving funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement RI-283493. A Marie Curie European Career Integration Grant within the 7th European Community Framework Programme and the Russian Foundation for Basic Research (Grant No. 11-03-01214) are acknowledged.

47 ESD 2013 Invited Talk No 32 I 32

The effect of a localized charge on the structure and stability of Van-der-Waals clusters

Y. Toker, I. Rahinov, D. Schwalm, O. Heber, M.L. Rappaport, D. Strasser and D. Zafjman

What is the effect of a localized charge on the structure and stability of Van-der-Waals

clusters? The simplest model system for answering this question is SF6 based clusters, since SF6 is a highly symmetrical molecule, and unlike noble gas clusters, the charge within the cluster is localized on one cluster unit. We have measured the binding energy + - for the cationic SF5 (SF6)N-1, and anionic (SF6)N series, using black-body induced radiative dissociation (BIRD). In the talk we will present our experimental approach which combines a supersonic expansion ion source and an electrostatic ion beam trap, along with the techniques of kick out-mass selection and pickup lifetime measurements.

[1] “Blackbody-induced radiative dissociation of cationic SF6 clusters”, Y. Toker, I. Rahinov, D. Schwalm, U. Even, O. Heber, M.L. Rappaport, D. Strasser and D. Zafjman, Phys. Rev. A. 86 (2012), 023202. [2] “The kick-out mass selection technique for ions stored in an Electrostatic Ion Beam Trap" Y. Toker, N. Altstein, O. Aviv, M.L.Rappaport, O. Heber, D. Schwalm, D. Strasser and D. Zajfman, JINST 4 (2009) P09001. [3] “Lifetime measurements in an electrostatic ion beam trap using image charge monitoring” I. Rahinov, Y. Toker, O. Heber, D. Strasser, M. Rappaport, D. Schwalm, D. Zajfman; Rev. Sci. Inst. 83 (2012), 033302.

48 Abstracts of Contributions

49 50 ESD 2013 Contributed Poster No 1 C 1

Modeling electron and energy transfer processes in collisions between ions and Polycyclic Aromatic Hydrocarbon molecules

John Alexander1, Tao Chen1, Björn Forsberg1, Alf Pettersson1, Michael Gatchell1, Henrik Cederquist1, Henning Zettergren1

1Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden

E-mail: [email protected]

Polycyclic Aromatic Hydrocarbons (PAHs) are believed to be an important component of the interstellar medium (ISM) [1]. Until now, the heating of PAHs in such environments has been assumed to be predominantly due to UV-absorption, where they subsequently cool down by IR-emission or statistical fragmentation through H-loss or C2H2-loss processes. However, collisions between keV ions and PAHs have gained recent interest [2, 3, 4, 5], as they may for instance be important in the processing of PAHs in shocks driven by supernova explosions. In this work we have used two models which describe interactions where the PAHs may be ionized and moderately heated in distant collisions or strongly heated in penetrating ion collisions, respectively.

In the first model an over-the-barrier approach was used to describe distant electron transfer collisions [6]. In order to take the orientation dependent polarization effects into account, the PAHs were modeled as infinitely thin and perfectly circular conducting disks. We calculate the absolute charge exchange cross-sections for a selection of planar almost circular PAHs (pyrene C14H10, coronene C24H12 and circumcoronene C54H18). The relative ionization cross- sections obtained from the model were found to compare favorably with the corresponding experimental results.

In the second model, we use well-known expressions for nuclear [7] and electronic stopping [2] processes to describe penetrating collisions. Here, we incorporate the actual molecular structures obtained from Density Functional Theory calculations. We have calculated the stopping energies as a function of PAH size and centre-of-mass energy, and for different collision partners. The model results suggest that non-statistical fragmentation processes, i.e. single atom knock-outs due to nuclear stopping processes, may be important for astrophysically relevant collision systems (He+PAH collisions at 100 eV centre-of-mass energies). This is consistent with recent experimental results from Stockholm University. Such collisions may thus induce highly reactive species with unsaturated carbon atoms, which is not possible in statistical processes following, for example UV-absorption. These types of collisions may therefore be an important initial step in molecular growth processes, as have been recently demonstrated in collisions between alpha particles and clusters of fullerenes carried out at the ARIBE facility in Caen, France.

References [1] A. G. G. M. Tielens, Annu. Rev. Astron. Astrophys. 46, 289 (2008). [2] J. Postma, et al, ApJ 708, 435 (2010). [3] A. Lawicki, et al, Phys. Rev. A 83, 022704 (2011). [4] G. Reitsma, et al, J. Phys. B 45, 215201 (2012). [5] E. R. Micelotta, et al, A&A A 36, 510 (2010). [6] B. O. Forsberg, et al, J. Chem. Phys. 138, 054306 (2013). [7] M. C. Larsen, et al, Eur. Phys. J. D 5, 283 (1999).

51 ESD 2013 Contributed Poster No 2 C 2

A Detector for 3D Molecular Fragmentation Imaging at the Cryogenic Storage Ring

A. Becker1, C. Krantz1, O. Novotný2, K. Spruck3, X. Urbain4, S. Vogel1 and A. Wolf1

1 Max-Planck-Institut für Kernphysik, Heidelberg 2 Columbia Astrophysics Laboratory, New York, USA 3 Institut für Atom- und Molekülphysik, Gießen 4 Université catholique de Louvain, Louvain-la-Neuve, Belgium

[email protected]

The electrostatic Cryogenic Storage Ring (CSR), currently under construction at the Max Planck Institute for Nuclear Physics in Heidelberg, will enable long time storage of slow molecular ions with energies up to 300 keV per unit charge in an environment with low blackbody radiation corresponding to the 10 K temperature of the storage ring enclosure. Under these conditions polyatomic ions up to high masses can be prepared in or near the rovibrational ground state. Their fragmentation can be studied by fast-beam coincidence fragment momentum imaging.

A detection system for 3D imaging of coincident neutral fragments from dissociative recombination reactions has been developed. The detector consists of two MCPs in Chevron configuration with an active diameter of 120 mm and a phosphor screen operated inside the CSR cryostat. The phosphor screen will be observed from outside the CSR cryostat by a fast camera system developed at UCL, Louvain-la-Neuve. The requirements of the CSR regarding the huge temperature range from operation at 10 K to bake-out at 520 K as well as an extremely high vacuum of better than 10-13 mbar placed strong demands on the design. In addition the dead time and timing resolution has to be in the ns range or better in order to temporally distinguish between impinging particles from each dissociation event.

The detector system will be installed already for the first commissioning phase of the CSR and used for the first experiments at cryogenic temperature conditions. The final design of this cryogenic detection system will be presented.

The detector development for the study of Cold Molecular Ions is funded within the DFG Priority Program 1573: Physics of the Interstellar Medium.

52 ESD 2013 Contributed Poster No 3 C 3

Probing reactive processes in a 22pole Ion Trap with a Multicycle Reflectron based TOF detector

E. Endres, D. Hauser, O. Lakhmanskaya, T. Best, and R. Wester

Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, A-6020 Austria

E-mail: [email protected].

A better understanding of gas-phase ion-molecule reactions enables progress in such diverse fields as atmospheric science, combustion processes or astrochemistry. Only few of these processes can be effectively studied in situ, so powerful tools such as drift tubes and guided ion beams have been developed. However, these tools are not particularly suited to investigate processes which process at a low rate, with complicated, possibly temperature-dependent product branchings, or multistep processes where products continue to react with the neutral educt. To study such processes, ion traps coupled to mass spectrometric detectors provide a great step forward both in terms of selectivity and sensitivity. Compared to more conventional quadrupole mass spectrometers, time-of-flight (TOF) detection allows for parallel detection of remaining educt ions, possible intermediate, and or or several products, thereby reducing the influence of ion source fluctuations and reducing overall measurement time. We have recently demonstrated the combination of a 22pole radio-frequency ion trap with a multicycle reflectron used as a TOF mass spectrometer. Here, we present recent experiments aimed at investigating ion-molecule reactions taking place at very low rates, with rate coefficients below 10-15 cm3/s, clearly beyond reach for conventional methods. Especially in the astrochemical context, of cold molecular clouds, even such low rate reactions may become important, as competing reactive pathways may be completely frozen out at the prevailing low temperatures, or suppressed due to the extremely low abundances of suitable reaction partners.

53 ESD 2013 Contributed Poster No 4 C 4

Investigation of radiative cooling of small metal cluster anions by laser-induced electron detachment

Christian Breitenfeldt1, Klaus Blaum2, Michael Froese2, Sebastian George1,2, Michael Lange2, Sebastian Menk2, Lutz Schweikhard1, Andreas Wolf2

1Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, Felix-Hausdorff-Str. 6, 17487 Greifswald, Germany 2Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany

E-mail: [email protected]

Radiative cooling is a fundamental process that determines the internal temperature of vibrationally excited ions as a function of time, eventually bringing them into thermal - equilibrium with their environment. We have investigated the cooling of Cun (n=4,5,6,7) and - Con (n=3, 4) anions.

The cluster ions were produced in a Cs sputter ion source, with a vibrational excitation corresponding to temperatures of several thousand Kelvins. They were then size-selected and transferred to the Cryogenic Trap for Fast ion beams (CTF) [1] within 120 µs, where they were stored at a kinetic energy of 6 keV. This electrostatic ion beam trap can be kept at a temperature below 15 K by a closed-cycle helium refrigeration system. The extremely low pressure (few 10-12 mbar) achieved by cryopumping resulted in a very low background of collision-induced ion loss and thus a beam lifetime of several minutes.

We have studied vibrational autodetachment (also called delayed detachment) by recording the rate of neutral particles escaping from the trap, as a function of the delay after the pulses from a laser emitting at a wavelength of 1064 nm. The rate for this process persists up to 3 ms after each laser pulse and approximately follows a power law in time. As the slope of the decay curve depends on the population of rotational and vibrational levels in the beam just before excitation, it can be used to probe the population of the stored ions [2].

- For Co4 we have studied the rate of delayed detachment as a function of storage time and photon energy in the wavelength region of 500 to 1500 nm. Again the number of clusters which undergo vibrational autodetachment depends on their internal energy and thus can be used to probe the vibrational population of the stored ions. For short wavelength no delayed detachment rate is observed. For increased wavelengths the detected rate increases with time in the period immediately after injection of the clusters into the CTF, before decreasing again or staying constant. For even longer wavelengths only a fast decrease of autodetachment rate is observed.

References [1] M. Lange et al., Review of Scientific Instruments, 81, 055105 (2010). [2] M. Lange et al., New Journal of Physics, 14, 065507 (2012).

54 ESD 2013 Contributed Poster No 5 C 5

Delayed emission in small carbon cluster anions

V. Chandrasekaran1, H. Rubinstein1, B. Kafle1 , Y. Toker1 , O. Heber1 , M. L. Rappaport1 , D. Schwalm1,2 and D. Zajfman1 1 Department of Particle Physics, Weizmann Institute of Science, Rehovot, 76100, Israel 2 Max-Planck-Institut für Kernphysik, D-69117 Heidelberg, Germany

E-mail: [email protected]

The delayed emission of C6 anions stored in electrostatic ion beam trap and excited by a laser pulse was measured. Preliminary results indicate a marked difference between the decay following the absorption of two photons compared the decay after the absorption of a single photon with similar total energy. In earlier photoelectron spectroscopic experiments, delayed electron emission has been observed for several nano-seconds by two photons absorption [1]. In this work, the decay rate after two photon excitation was measured to be several microseconds while the decay rate after single photon absorption was several milliseconds. These different decay rates indicate that statistical dissociation alone cannot account for both cases, but that an additional process is involved.

References [1] Zhao, Y.; De Beer, E.; Xu, C.; Taylor, T.; Neumark, D. M., The Journal of Chemical Physics, 105, 4905 (1996).

55 ESD 2013 Contributed Poster No 6 C 6

K-Shell Photoionization in the Nitrogen Isonuclear Sequence

M. F. Gharaibeh1, J. M. Bizau2,3, D. Cubaynes2,3, S. Guilbaud2, N. El Hassan2, M. M. Al Shorman2, C. Miron3, C. Nicolas3, E. Robert3, I. Sakho4, C. Blancard5 and B. M. McLaughlin6,7

1Department of Physics, Jordan University of Science and Technology, Irbid 22110, Jordan 2 Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS UMR 8214, Université Paris-Sud, Bât. 350, F-91405 Orsay cedex, France 3Synchrotron SOLEIL - L'Orme des Merisiers, Saint-Aubin - BP 48 91192 Gif-sur-Yvette cedex, France 4UFR Sciences and Technologies, Department of Physics, University of Ziguinchor, 523 Ziguinchor, Senegal 5CEA-DAM-DIF, Bruyères-le-Châtel, F-91297 Arpajon Cedex, France 6Centre for Theoretical Atomic, Molecular and Optical Physics (CTAMOP), School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, Northern Ireland, UK 7Institute for Theoretical Atomic and Molecular Physics (ITAMP), Harvard Smithsonian Center for Astrophysics, MS-14, Cambridge, MA 02138,USA

E-mail: [email protected]

Satellites Chandra and XMM-Newton currently provide a wealth of x-ray spectra of astronomical objects; however, a serious lack of high quality atomic data impedes the interpretation of these spectra [1]. Spectroscopy in the soft x-ray region (5-45 Å) including K- shell transitions of C, N, O, Ne, S and Si, in neutral, singly or doubly ionized states and L- shell transitions of Fe and Ni, provides a valuable tool for probing the extreme environments in active galactic nuclei (AGN's), x-ray binary systems, cataclysmic variable stars (CV's) and Wolf-Rayet Stars [2].

Absolute cross sections for the K-shell photoionization of nitrogen ions from C-like to Li-like were measured by employing the ion-photon merged-beam technique at the new MAIA (Multi-Analysis Ion Apparatus) set-up permanently installed on Branch A of the PLEIADES beamline at the SOLEIL, the French national synchrotron radiation facility in Saint-Aubin. Nitrogen ions are produced in the gas-phase using a 12.6 Ghz electron-cyclotron-radiation ion-source (ECRIS). The photon beam is monochromatized synchrotron radiation from the PLEIADES beamline. Two undulators with 256 mm and 80 mm period deliver photons in the 10 - 100 eV and 100 – 1000 eV energy ranges, respectively, with all types of polarization above 55 eV. High-resolution spectroscopy with E/E up to 7,000 was achieved with the photon energy from 388 to 470 eV scanned for each ions. Experimental results are compared with theoretical predictions made from Screening Constant by Unit Nuclear Charge (SCUNC), the multi-configuration Dirac-Fock (MCDF) and R-matrix methods. The combination of experiment and theory enabled the identification and characterization of the strong 1s → 2p resonances observed in the spectra. The first experimental data of our work on N+ has been published in Journal of Physics B: Atomic, Molecular and Optical Physics [3].

References [1] B M McLaughlin, “Spectroscopic Challenges of Photoionized Plasma” in ASP Conf. Series vol 247, edited by G. Ferland and D. W. Savin, San Francisco, CA: Astronomical Society of the Pacific, 2001, pp 87. [2] Skinner S L et al, Astronom. J., 139, 825 (2010). [3] M F Gharaibeh, J Phys B: At. Mol. Opt. Phys., 44, 175208 (2011).

56 ESD 2013 Contributed Poster No 7 C 7

Space-Charge Dynamics in a Multi-Reflection Ion Trap

A. Giannakopulos 1, D. Grinfeld 1, I. Kopaev 2, A. Makarov 1, M. Monastyrskiy 2, M. Skoblin 3

1 Thermo Fisher Scientific, Bremen, Germany 2 General Physics Institute of Russian Academy of Science, Moscow, Russia 3 Institute for energy problems of chemical physics, Russian Academy of Science, Moscow, Russia

E-mail: [email protected]

In the multi-reflection traps the ions are confined between a pair of electrostatic mirrors, making multiple reflections in each mirror successively. In case that the paraxial transfer matrix has only unimodular eigenvalues at an oscillation, the ion motion is absolutely stable [1] and the travel length may reach several kilometers being only restricted by the residual gas collisions. The electrostatic multi-reflection traps may also be optimized to acquire isochronous properties, so that the ion oscillation period is practically independent of the ion’s full energy and other parameters but the mass-to-charge ratio only [2]. Isochronous ion traps offer a lot of opportunities for the time-of-flight mass spectrometry (ToF MS), with the mass resolving power approaching that of the Fourier transform mass spectrometric (FT MS) methods, but winning in the analysis time and sensitivity.

One of the simplest ion traps of this type comprises two identical axisymmetric ion mirrors facing each other and leaving a field-free region in-between. Each mirror contains four cylindrical electrodes whose geometries and voltages guarantee the stability criterion and eliminate most critical time-of-flight aberrations. As a result, the ion oscillation period is practically independent of energy in a wide range   , the error being as small as O ( 4 ) . The second-order position/angular aberrations also vanish.

The ions, after preliminarily storing and cooling in a RF quadrupole trap, are ejected by an accelerating electric field, strong enough to suppress the turn-around temporal spread. A system of deflectors steers the ion bunch into the multi-reflection trap. Upon multiple oscillations, the mass-separated ion bunch is deflected out of the trap to impinge a time- resolving MCP detector. The mass resolving power of 79,000 is achieved at 100 oscillations.

Our experiments show significant deterioration of the mass-resolving performance by the space charge, which restricts the maximum number of ions capable of being analyzed in one run. The theory and computer simulations reveal that the most critical space-charge interactions have the resonant nature and occur between ions of the same sort or between those with close masses, e.g. different isotope states. The experimental and simulation analysis of the self-bunching and coalescence effects in the trapped ion bunches is presented and discussed.

References [1] Verentchikov A., Berdnikov A., and Yavor M., Physics Procedia 1(1), p. 87–97 (2008). [2] Wollnik H. and Casares A., Int. J. Mass Spectrom. 227, p. 217–222 (2003).

57 ESD 2013 Contributed Poster No 8 C 8

A versatile ion-neutral collision setup for the CSR

F. Grussie1, F. Berg1, M. Grieser1, A.P. O’Connor1, and H. Kreckel1

1 Max Planck Institut für Kernphysik, Heidelberg

E-mail: [email protected]

Collisions between molecular and atomic ions and neutral atoms are among the most frequent processes in the universe. A lot of experimental work on ion-atom collisions has been done in selected-ion flow tubes and afterglows, however, all of these plasma measurements are carried out at room temperature and at relatively high pressures. Recent measurements studying CH+ + H collisions in a temperature-variable ion trap [1] have shown that ion-neutral rate coefficients – in contrast to the simplifying Langevin collision rate – can depend strongly on temperature. To address this important class of reactions, we are currently developing a versatile ion- neutral collision facility for the Cryogenic Storage Ring (CSR) to perform measurements of some of the most important interstellar ion-atom collisions. We will use the proven merged- beams technique to cover the entire relevant temperature range from 40-40000 K. With the unique combination of state-selective stored ions at temperatures down to 10 K and laser- generated, ground-state H, D, O or C atom beams, we will be able to perform detailed energy- resolved measurements that further our knowledge of molecule formation in interstellar space.

References

[1] R. Plasil et al., Astrophys. J. 737, 60 (2011)

58 ESD 2013 Contributed Poster No 9 C 9

The prompt and delayed dissociation of Pyrene cation in the Miniring

M. Ji1, C. Ortéga1, R. Brédy1, J. Bernard1, L. Chen1, G. Montagne1, A. Cassimi2, Y. Ngono-Ravache2, C. Joblin3 and S. Martin1

1 Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex, France 2 CIMAP, GANIL Université de CAEN, Bd. H. Becquerel, Caen, France 3 Université de Toulouse, UPS-OMP, IRAP, Toulouse, France

E-mail: [email protected]

+ We have stored pyrene cations (C16H10 ) in an electrostatic storage ring called Miniring, which is composed of two straight sections [1]. The pyrene cations from an ECR ion source were accelerated to 12 keV and injected into the ring via the first straight section. The neutral fragments emitted due to dissociation along the second straight section were collected by a MCP detector. In order to detect both the prompt and delayed laser-induced dissociation of pyrene cations, a laser pulse was sent through the center of the second straight section at a controlled storage time. Figure 1 shows a laser-induced dissociation spectrum recorded when the laser pulse was fired after a storage time of 1.5 ms; the first peak was contributed by the neutrals emitted in prompt dissociation during the first 0.4 µs after laser excitation.

Figure 1. Laser-induced prompt and delayed dissociation spectrum with laser pulse fired after a storage time of 1.5 ms, the photon energy h=2.33 eV. The prompt dissociation yield has been divided by a factor of 15.

We have measured the dissociation spectrum as a function of the power of the laser. It was deduced that the prompt dissociation was due to the contribution of a mixture of two photon and three photon absorption, and the delayed dissociation was mainly due to two photon absorption.

References [1] J. Bernard et al. 2008 Rev. Sci. Instrum. 79 075109 (2008)

59 ESD 2013 Contributed Poster No 10 C 10

Charge separation and the early stages of dissolution in hydrated salt clusters

C. Johnson, C. Leavitt and M. Johnson

Sterling Chemistry Laboratory, Department of Chemistry, Yale University, 225 Prospect St., New Haven, CT, 06511

E-mail: [email protected]

We investigate the intermolecular interactions involved in the first steps of salt dissolution by Cryogenic Infrared Vibrational Predissociation spectroscopy of cold (~35 K), tagged, size- selected hydrated salt clusters. These clusters are produced by electrospray ionization of salt solutions and transferred to a 10 K Paul trap where they are cooled so that messenger “tag” molecules (D2, N2) condense on them. From the trap they are extracted into a tandem time- of-flight mass spectrometer and interrogated by a tunable infrared laser system. For + MOH (H2O)n (M=Mg, Ca, n=1-6) clusters we follow the evolution of the OH stretching bands with increasing hydration. The spectra show that the once-distinct hydroxide stretch becomes indistinguishable from the water OH stretches, signaling the beginning of dissolution to M2+ + OH– as the hydroxide begins to integrate into the water network. Simultaneously, an extremely broad (~500 cm-1 FWHM), red-shifted OH stretching band appears which is attributed to large-scale motion of shared protons in the water network. Calculations show that these phenomena occur at size ranges where hydration in the second water shell becomes energetically competitive with first shell hydration. Additionally, infrared spectra of the 2+ cluster [(H2O)nMgSO4Mg(H2O)m] reveal the striking effect of asymmetric solvation (n ≠ m) of the Mg cations on the splitting of the nominally degenerate SO4 asymmetric stretching bands. This splitting is tracked to the partial dissolution of the more hydrated Mg cation.

60 ESD 2013 Contributed Poster No 11 C 11

A Laser Vaporization (LVAP) metal ion cluster source

T. Kolling1, M. Tombers1 and G. Niedner-Schatteburg1

1 TU Kaiserslautern, Fachbereich Chemie

E-mail: [email protected]

Studies of metal and transition metal cluster ions in the gas phase are of great importance and interest in scientific research and development. A wide range of reactions of molecules with metal and transition metal cluster ions are under examination and of interest [1, 2]. There is equal interest in the investigation of magnetic properties of metal clusters [3, 4]. We present our dedicated laser vaporization metal ion cluster source, which serves in such investigations. In addition, it allows for the formation of metal cluster rear gas complexes in copious amounts.

+ Figure1: Exemplified the figure shows a mass spectra of cationic tantalum cluster ions Tan + (with n = 2 – 30) and tantalum-argon-complexes [TanArm] (with n = 2 – 10, m = 1 – 2) [5]. References [1] Christian Berg, Thomas Schindler, Gereon NiednerSchatteburg, and Vladimir E. Bondybey; J. Chem. Phys., 102, 4870-4884, (1995). [2] Tombers, M.; Barzen, L.; Niedner-Schatteburg, G., Journal of Physical Chemistry A, 117, 1197 (2013). [3] Peredkov, S.; Savci, A.; Peters, S.; Neeb, M.; Eberhardt, W.; Kampschulte, H.; Meyer, J.; Tombers, M.; Hofferberth, B.; Menges, F.; Niedner-Schatteburg, G. J. Electron Spectrosc. Relat. Phenom, 184, 113-118 (2011). [4] Peredkov, S.; Neeb, M.; Eberhardt, W.; Meyer, J.; Tombers, M.; Kampschulte, H.; Niedner- Schatteburg, G., Physical Review Letters, 107, 233401 (2011). [5] Meyer, Jennifer; Diploma Thesis, (2009).

61 ESD 2013 Contributed Poster No 12 C 12

Combining experimental techniques for comprehensive case studies of molecular astrophysics

H. Kreckel1, F. Grussie1, A.P. O’Connor1, A. Becker1, C. Krantz1, O. Novotny2,1, and A. Wolf1

1 Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany 2 Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA

E-mail: [email protected]

As an ever increasing number of molecules are observed in interstellar space, accurate laboratory data on their formation and destruction processes will be required to understand interstellar reaction networks. Astrochemical models have identified ion-molecule reactions as one of the drivers for the buildup of molecules in space. On the other hand, dissociative recombination with free electrons often terminates an ionic reaction chain and determines which neutral products are being formed. In order to model the abundance of individual species reliably, energy-resolved rate coefficients for all the competing processes will be required. At the Max-Planck-Institute for Nuclear Physics we intend to combine various experimental techniques to yield a comprehensive description of the relevant reactions for chosen important species. The new Cryogenic Storage Ring (CSR) will be equipped with a low-energy electron cooler and a neutral atom beamline. These facilities will allow for absolute rate coefficient measurements of dissociative recombination (DR) and ion-atom collision processes, involving cold molecular ions. Furthermore, a cryogenic 22-pole ion trap can be used for pre-cooling molecular ions, performing reaction studies with cold neutral molecules, and state-specific spectroscopy at variable temperatures. With these techniques we aim to shed light on the puzzling nuclear spin distribution observed + for interstellar H3 [1], where exchange reactions with molecular hydrogen play a role, as well + as the nuclear-spin dependence of the DR reaction with cold H3 . Furthermore, we will + investigate the gas-phase route to water formation, which begins with H3 + O collisions and + ends in the DR of cold H3O , resulting in the formation of water in space [2]. Additional fields of research will be the formation and destruction of organic molecules under interstellar conditions and early universe chemistry.

References

[1] K.N. Crabtree, N. Indriolo, H. Kreckel, B.A. Tom, B.J. McCall, Astrophys. J. 729, 15 (2011). [2] H. Buhr et al., Phys. Rev. Lett. 105, 103202 (2010)

62 ESD 2013 Contributed Poster No 13 C 13

Limits to the Persistence of Self-Synchronized Bunches in an Electrostatic Ion Beam Trap

Michael Lange1, Klaus Blaum1, Christian Breitenfeldt2, Michael Froese1, Sebastian George1,2, Manfred Grieser1, Sebastian Menk1, Lutz Schweikhard2, Andreas Wolf1

1Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany 2Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17487 Greifswald, Germany

E-mail: [email protected]

One of the interesting properties of electrostatic ion beam traps is that they allow the non- destructive measurement of the mass of the stored ions: The ions passing back and forth through a ring electrode produce image charges, which can be picked up as periodic voltage signals with a frequency characteristic of their mass. As single ions can usually not be detected, the measurement is performed on a coherently moving bunch of ions. The precision of this measurement is limited by the observation time. After its injection a bunch normally disperses within milliseconds due to the unavoidable spread of the ions’ orbital frequencies. In the so-called self-bunching mode, negative orbital frequency dispersion is introduced that combines with the Coulomb repulsion between the ions. This procedure counteracts the frequency spread and keeps the ion bunch coherent for an extended period of time [1].

Using the extremely long ion storage times of several minutes afforded by the extreme vacuum of the Cryogenic Trap for Fast ion beams (CTF [2]) we have previously observed self-synchronized bunches to persist for up to 12 s [3]. In addition, we have found a correlation between the initial signal amplitude and the lifetime of the bunches. The time dependence of the pick-up signal obtained from a spectrum analyzer was well reproduced by a model assuming both a broadening of the longitudinal bunch dimension and a loss of ions into a continuous beam by collisions with other ions or residual gas. In a more extensive investigation of bunch decay, we have explored its dependence on various parameters of both the ions and the trap. Most notably, we have found that the bunch lifetime does not surpass a certain limit, even if the bunch charge is increased further. Within our earlier model, this is attributed to intra-beam scattering. The rate of this loss increases quadratically with the number of ions, so that all particles above a certain threshold number are removed from the bunch on a time scale much shorter than the bunch lifetime. After this initial rapid loss, all bunches above the threshold continue with very similar ion numbers and hence exhibit similar decays. We have also explored the relation between the maximum bunch lifetime and the ion mass, where we have found that the former scales only with the ion’s orbital period, i.e. that bunches persists for a maximum number of orbits that is independent of the particle mass.

References [1] H. B. Pedersen et al, Phys. Rev. Lett. 87, 055001 (2001). [2] M. Lange et al., Rev. Sci. Instrum. 81, 055105 (2010). [3] M. Froese et al., New. J. Phys. 14, 073010, (2012).

63 ESD 2013 Contributed Poster No 14 C 14

Construction of a tabletop electrostatic storage ring

J. Matsumoto, K. Gouda and H. Shiromaru

Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan

E-mail: [email protected]

We are constructing a tabletop electrostatic ion storage ring (E-ring), which is about one- tenth the size of the existing ring at Tokyo Metropolitan University [1] with keeping arrangement of the ion beam optics. The compact size of the ring has great advantages; owing to a short period of revolution, higher time resolution of observations would be achieved. Therefore, the E-ring will complement single-pass experimental apparatus and the existing electrostatic ion storage rings as for the observation of microsecond to millisecond time scale dynamics. In addition, the compact design will enable us to bring it to various ion beam facilities. The E-ring consists of two 160-degree deflectors, four 10-degree deflectors, and four focusing and defocusing electrostatic quadrupole doublets, a picture of which is shown in Fig. 1. It is designed for storage of positive or negative ions with the energy range from several to 20 keV with the storage time up to several seconds under an ultra-high vacuum (10-9 Pa). The dimensions of each electrode were optimized with considering accuracy of machining and assemblage required due to the miniaturization. The circumference of an ion beam trajectory is about 0.8 m, and all electrodes are mounted on a single rectangle plate of 480 mm x 200 mm, for precise alignment of the electrodes and efficient bake-out of the ring. In the presentation, we will show the detailed design and the status of the E-ring.

Figure 1. A picture of the E-ring, which consists of 160-degree deflectors, 10-degree deflectors, and focusing and defocusing electrostatic quadrupole doublets, mounted on the aluminum plate.

References [1] S. Jinno et al., Nucl. Instrum. Meth. A, 532, 477 (2004).

64 ESD 2013 Contributed Poster No 15 C 15

Status of the injection beamline for the cryogenic electrostatic storage ring at RIKEN

Y. Nakano1, T. Masunaga1, Y. Enomoto1 and T. Azuma1,2

1 AMO Physics Lab., RIKEN, Saitama, Japan 2 Dept. of Physics, Tokyo Metropolitan University, Tokyo, Japan E-mail:[email protected]

We report on the designing and current status of the new beamline developed for the cryogenic electrostatic storage ring at RIKEN. The storage ring will be equipped with two injection beam lines; one is dedicated to the molecular ion injection to the ring, and the other serves as the laser and neutral beam injector for the merged-beam experiments. Currently, the ion injection beamline is prepared for the first test of the storage ring operation with atomic ions from an ECR ion source. The beamline optics was designed to transport the 10-30q keV positive/negative ions with optimum beam quality, which consists of several focusing and steering components as well as beam diagnostic systems. The basic part of the beamline is shown in Figure 1. The beam shape, position, and intensity can be monitored by the beam position monitor (MCP + phosphor screen) and movable four-jaw slits as Faraday plates. To ensure the extremely high vacuum condition of the storage ring, a differential pumping chamber was installed at the end of the beamline, which achieved 8x10-8 Pa without bake-out. After the R&D of the storage ring with atomic ions, a molecular ion source will be installed with a 4K ion trap. Preparation of the laser/neutral beamline is concurrently running.

Figure 1: The layout of the ion injection beamline; 1: differential pumping chamber, 2: XY slit, 3: beam chopper, 4: beam position monitor, 5: beam steerer, 6: quadrupole triplet, 7: XY slit, 8: quadrupole beam deflector, 9: einzel lens, 10: XY slit, 11: beam chopper, 12: dipole magnet of the ECR ion source.

65 ESD 2013 Contributed Poster No 16 C 16

Calorimeter detector for fragmentation studies at CSR

O. Novotný1,2, L. Gamer3, C. Krantz2, A. Pabinger3, C. Pies3, C. Enss3, D.W. Savin1, A. Fleischmann3, and A. Wolf2

1 Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA 2 Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany 3 Kirchhoff Institute for Physics, Heidelberg University, INF 227, 69120 Heidelberg, Germany

E-mail: [email protected]

Dissociative recombination (DR) of electrons with molecular ions is important in a wide range of plasmas, such as interstellar clouds, planetary ionospheres, etching plasmas, and divertor plasmas in fusion devices [1]. Studies of these environments often rely on numerical models of the underlying chemistry. Reliable DR data are needed for these models. Until recently most of the DR data were measured in experiments at magnetic storage rings, such as TSR. In that work, the Si surface-barrier detectors provided the critical DR parameters, i.e., the total rate coefficient and branching ratios for various fragmentation and excitation product channels.

Unfortunately, Si surface-barrier detectors cannot be used for upcoming DR experiments at the Cryogenic Storage Ring (CSR). Here the maximal ion beam energies of ~300 keV will result in DR products with kinetic energy too low to penetrate through the non-sensitive surface layer of a surface-barrier detector. Therefore we plan to use a metallic magnetic calorimeter detector (MMC) which does not suffer from such limitations [2].

The extremely high energy resolution of the MMC detectors is commonly employed for studies in X-ray spectroscopy [3]. For the DR experiment we will modify the MMC detector design so that it provides not only a high resolution on kinetic energy of the DR fragments, but also transverse positions of incident DR fragments. The measured fragment kinetic energy will be used to distinguish the fragments by their mass and thus determine the fragmentation channel for each DR event. The spatial resolution will provide information on the kinetic energy released in a given DR channel. From this, e.g., the product excitation states can be determined.

At the poster we will present the MMC detector design as planned for the DR experiments at CSR. Additionally we will discuss the MMC detector kinetic energy resolution for ~keV massive particles.

References [1] M. Larsson and A. Orel, Dissociative Recombination of Molecular Ions 1st ed., Cambridge: Cambridge University Press (2008) [2] C. Enss (ed.), "Cryogenic Particle Detection", Topic of Applied Physics 99, Springer-Verlag Berlin Heidelberg (2005) [3] C. Pies et al., J. Low Temp. Phys., 167(3/4), 269 (2012).

66 ESD 2013 Contributed Poster No 17 C 17

Measurement of PAH Kinetic Energy Release (KER) in the Mini- Ring

C. Ortéga1, R. Brédy1, M. Ji1, J. Bernard1, G. Montagne1, A. Cassimi2, Y. Ngono-Ravache2, C. Joblin3, L. Chen1 and S. Martin1

1 Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex, France 2 CIMAP, GANIL Université de CAEN, Bd. H. Becquerel, Caen, France 3 Université de Toulouse, UPS-OMP, IRAP, Toulouse, France

E-mail: [email protected]

It is well-known that excited Polycyclic Aromatic Hydrocarbons dissociate mainly by the loss of H or C2H2. The branching ratios between this two dissociation processes depend on PAH structure and energy: for high internal excitation energy, the loss of H is the dominant channel [1]. The latest development around our compact electrostatic ion storage ring, so-called Mini-Ring [2], is an upgrade of the detection system: a position sensitive detector (PSD) records the position of the neutral exiting the ring at each turn. The partial projection of the image provides information on the Kinetic Energy Release (KER) of the dissociation process. The aim is to measure the KER evolution and to determine the branching ratios for H and C2H2 dissociation as a function of the molecule internal energy.

Figure 1. Image from the position sensitive detector. Pyrene+ at 12keV is stored on the Mini-Ring. The intense spot on the left on the image is principally due to C2H2. And the other points on the entire detector are due to H. A partial projection of the image is shown. From this projection, it is possible to determine the KER distribution of the 12keV Pyrene+ dissociation process.

References [1] S. Martin et al, Physical Review A, 85, 052715 (2012). [2] J. Bernard et al, Review of scientific instruments, 79, 075109 (2008).

67 ESD 2013 Contributed Poster No 18 C 18

Electron Velocity Map Imaging in an Electrostatic Ion Beam Trap

A.Prabhakaran, M.Rappaport, Y.Toker, O.Heber, D.Schwalm, D.Zajfman.

Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Israel.

E-mail: [email protected]

One of the main advantages of electrostatic ion beam traps (EIBT) [1,2], in which keV- ions are kept oscillating for seconds between two electrostatic mirrors, is the large field-free region in the center of the trap. The high energy and the directional focusing of heavy fragments from reactions processes induced to the stored ions allow the detection of these products with high efficiency. The field free region facilitates the incorporation of targets [3] and additional detectors [4] into the trap. Recently, a velocity-map imaging (VMI) photo- electron detector has been integrated into a cryogenically cooled EIBT by Johnson et al. [5] to investigating photo-dissociation dynamics of molecules by electron-fragment coincidence. We are presently designing a VMI system to be incorporated into our bent EIBT setup [4]. Photo-electrons induced by a short laser pulse will be extracted by a small electrostatic field perpendicular to the ion beam, and accelerated towards a position sensitive detector. To correct for the deflection of the ion beam by the extraction field the repeller of the standard VMI design is split into a repeller and a corrector which are oppositely biased. In addition, however, our design also contains an Einzel lens which which allows to alternate the magnification while maintaining the focus of the VMI electrons. SIMION [6] program was used to optimize the design and to investigate its properties. The design and simulation results of the VMI system are presented.

References [1] D. Zajfman, O.Heber, L.V.Christensen, I.B.Itzhak, M.Rappaport, R.Fishman, M.Dahan, Phys. Rev. A, 55, R1577 (1997). [2] M.Dahan, R.Fishman, O.Heber, M.Rappaport, N.Alstein, D.Zajfman, W.J.van der Zande, Rev. Sci.Instrum., 69, 1 (1998). [3] O. Heber, P. D. Witte, A. Diner, K. G. Bhushan, D. Strasser, Y. Toker, M. L. Rappaport, I. Ben-itzhak, N. Altstein, D. Schwalm, A. Wolf, and D. Zajfman, Rev. Sci. Instrum. 76, 13104 (2005). [4] O. Aviv, Y. Toker, M. Errit, K. G. Bhushan, H. B. Pedersen, M. L. Rappaport, O. Heber, D. Schwalm, and D. Zajfman, Rev. Sci. Instrum. 79, 83110 (2008). [5] C. J. Johnson, B.B.Shen, B.L.J.Poad, R.E.Continetti, Rev. Sci. Instrum., 82, 105105 (2011). [6] SIMION V.8.0, Ions Source Software.

68 ESD 2013 Contributed Poster No 19 C 19

Monte Carlo simulations of  Correlation Precision Measurements of 6He+ in an Electrostatic Trap

M. Hass1, S. Vaintraub1,2, A. Prygarin1, A. Dhal1, O. Heber1,T. Hirsh2,. D. Melnik2, T. Kong1, M.L Rappaport1, G. Ron4, D. Schwalm1,3, T. Segal4, D. Zajfman1, K. Blaum3

1 Weizmann Institute of Science, Rehovot, Israel 2 Soreq Nuclear Research Center, Yavne 81800, Israel 3 Max-Planck-Institut für Kernphysik, D-69117 Heidelberg, Germany 4 The Hebrew University, Jerusalem, Israel

E-mail: [email protected]

Precision measurements of the angular correlation reveal the nature of the fundamental interactions and can shed light on the possible extensions of the Standard Model. Historically, the isotope 6He has been extensively used in determining the form of the weak interaction. The present experimental techniques may allow to measure the correlation coefficient at the precision level at which the Standard Model corrections and that of its possible extensions are of the same order, namely below 1%. We performed Monte Carlo simulations of the experimental setup consisting of 6He+ trapped in an electrostatic ion beam trap (EIBT), studying the interplay of different experimental parameters and their influence on the angular correlation coefficient. The bunch size of the trapped ions is of particular interest and it comprises the major factor in the estimations of the experimental precision. The simulations show low sensitivity to the size of the bunch and the presently available 2 cm size does allow measurements of the correlation coefficient at the level less than 1%. Alternatively, once can take an advantage of the fact that for zero neutrino mass the system is over-determined (one measures energy and momentum of electron and recoil ion, six measurable quantities in total, for five free parameters), which makes it possible to determine the profile of the ion bunch in the electrostatic ion beam trap (EIBT). This information is extremely useful since the bunching is independent of mass and should be the same for other ions of the same charge. We present simulation results relevant to the conceptual design of the EIBT setup at the WI.

69 ESD 2013 Contributed Poster No 20 C 20

A Cryogenic Electrostatic Ion Beam Trap to study molecular ions and clusters at 4 – 300 K

H. Rubinstein1, M. Rappaport1, Y. Toker1, V. Chandrasekaran1, O. Heber1, D. Schwalm1,2 and D. Zajfman1

1Weizmann Institute of Science, Rehovot 76100, Israel 2Max-Planck-Institute for Nuclear Physics, D 69117 Heidelberg, Germany

E-mail: [email protected]

Recently, two cryogenic electrostatic ion beam traps (EIBT) [1,2], based on the linear electrostatic resonator design that was developed at the Weizmann institute [3], have commenced operation. In this report, a third, innovative design of a cryogenic EIBT will be presented. Like the EIBT of Johnson et al. [2], it will be operated inside a Ø24” (Ø610 mm) chamber with wire-seal flanges and will be cooled by an SHE two-stage Gifford-McMahon cryocooler with a cooling power of 1.5 W at 4.2 K. The chamber will be pumped by a large

cryopump with pumping speed of 7,300 l/s for H2. Additional pumping of the trap itself will be provided by a UHV charcoal adsorber [4] located inside of, but not attached to, a copper box containing the trap. A He gas heat switch between the second stage of the cryocooler and the copper box should allow the trap to be heated to > 100 K without causing significant outgassing of the charcoal adsorber. The goal is to attain long storage times of keV ions and easy temperature control in the range from 4 K to at least 100 K by a combination of He pressure in the switch and heater power. In combination with a sputter or supersonic expansion ion source the trap will be used to study the cooling and heating mechanisms, respectively, of size-selected atomic and molecular clusters.

A report on the progress and a review of the methods and technologies used in this project will be presented.

References [1] M. Lange et al., Rev. Sci. Instrum. 81, 055105 (2010). [2] C. J. Johnson et al., Rev. Sci. Instrum. 82, 105105 (2011). [3] D. Zajfman et al., Phys. Rev. A, 55(3), R1577 (1997). [4] Produced by C. Day at Karlsruhe Institute of Technology.

70 ESD 2013 Contributed Poster No 21 C 21

Development and tests of a single particle counting detector for the CSR

K. Spruck1, A. Becker2, C. Krantz2, A. Müller1, O. Novotný3, A. Wolf2 and S. Schippers1

1 Institut für Atom- und Molekülphysik, Justus-Liebig Universität Gießen, D-35392 Gießen 2 Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg 3Columbia Astrophysics Laboratory, 550 West 120th Street, New York, NY 10027, USA

E-mail: [email protected]

The electrostatic Cryogenic Storage Ring (CSR) [1], currently under construction at the Max Planck Institute for Nuclear Physics in Heidelberg, will allow for experiments with atomic, molecular and cluster ions of energies up to 300 keV per unit charge in extreme high vacuum (XHV) condition. XHV will be achieved by cryopumping at 2 K in a chamber kept at about 10 K. Collisions of the stored ions with photons, electrons, or neutral particles will lead to reaction products with masses and/or charge states that differ from those of the primary particles. Detection of these reaction products requires a highly efficient large aperture single particle counting detector that is movable within the CSR cryostat and able to operate at the ambient temperature of approximately 10 K. A detector based on a converter plate and secondary electron detection by a microchannel plate has been simulated and designed. The layout is compatible with the cryogenic operating conditions and a high-temperature bakeout of up to 250°C. The detector will be mounted on a translation stage with a travel range of 400 mm inside the cryogenic XHV.

Components have been assembled and successfully tested at a temperature of about 20 K. Efficiency tests of the detector at room temperature have been performed.

As a potential alternative solution, an existing detector design based on a single channel electron multiplier, of known high detection efficiency [2] but of smaller sensitive area, has been tested for its cryogenic compatibility.

The detector setup as well as its performance tests will be presented. This work is funded within the DFG Priority Program 1573: Physics of the Interstellar Medium.

References [1] von Hahn et al., NIM-B, 269, 2871-2874 (2011). [2] Rinn et al., Rev. Sci. Instrum., 53, 829-837 (1982).

71 ESD 2013 Contributed Poster No 22 C 22

Status of FLSR

K.E. Stiebing1, D. Tiedemann1, R. Dörner1, F. King1, A. Jung1, M. Völp1 and A. Papash2

1 Institut für Kernphysik, J.W.Goethe-Universität, Max von Laue Str. 1, D-60438 Frankfurt am Main 2 Karlsruher Institut für Technologie, Institut für Synchrotronstrahlung, mbox 3640, D-76021 Karlsruhe

E-mail: [email protected]

The Frankfurt Low-Energy Storage-Ring (FLSR), is an electrostatic device for experimental research of the dynamics in atomic and molecular reactions. It is designed for an ion energies up to 50 q*keV [1]. After successful installation of the ion optical elements in the storage ring, the beam lines for the ion transfer from two ion sources and for the ion injection have been set up to provide the required parameters for the injection into the ring. These beam lines are presently under evaluation

In order to verify the calculated beam profile inside FLSR, we have constructed and inserted special scrapers and sector Faraday-Cups for beam diagnostics. They are suitable for the UHV environment of FLSR. These systems are integrated into the control system of the Ring by means of a 64-channel current read out system with a large dynamic range, allowing to measure down to currents in the 100 pA range. In addition, a variety of different ceramic materials is presently being studied for their long term use as optical viewers in the ring.

To identify possible sources of beam loss caused e.g. by fringe fields of the ion optical elements, which have not been taken into account in the grid simulations of FLSR, we have also performed extensive simulations with 3D-Computer codes. The results from these studies and the present status of the project will be reported and discussed.

References [1] K.E. Stiebing, V.Alexandrov , R.Dörner, S.Enz, N.Yu.Kazarinov, T.Kruppi, A.Schempp, H. Schmidt Böcking , M.Völp , P.Ziel , M.Dworak , W.Dilfer; Nuclear Instruments and Methods in Physics Research, A 614, 10–16(2010)

72 ESD 2013 Contributed Poster No 23 C 23

Design of a new position and energy sensitive electron detector

S. Vaintraub1,2, M. Hass1 , H. Edri1, A. Prygarin1 and T. Segal3

1 Weizmann Institute of Science, Rehovot, Israel 2 Soreq Nuclear Research Center, Yavne, Israel 3 The Hebrew University, Jerusalem, Israel

E-mail: [email protected]

A new conceptual design of an electron detector, which is position and energy sensitive, was developed. This detector is designed for beta decay energies up to 4 MeV, but in principle can be re-designed for higher energies. The detector setup includes one large plastic scintillator and, in general, not a large number of photomultipliers (7 presently). The current setup was designed and constructed after an extensive GEANT4 simulation study. By comparison of a single hit energy distribution between the various photomultipliers to a pre-measured accurate position-response map, the anticipated position resolution can be made much better that the size of each individual photomultiplier. First benchmark experiments have been conducted in order to calibrate and find the energy and position resolutions of the detector. The new method, results of the benchmark experiments and comparison to simulations will be presented for the first time.

73 ESD 2013 Contributed Poster No 24 C 24

Status of the low-energy electron cooler for the Cryogenic Storage Ring

Stephen Vogel*, Klaus Blaum, Claude Krantz, Andrey Shornikov, and Andreas Wolf

Max-Planck-Institut für Kernphysik, Heidelberg E-mail: [email protected]

The Cryogenic Storage Ring (CSR) is currently under construction at the Max Planck Institute for Nuclear Physics in Heidelberg. It will feature a low-energy electron cooler allowing to cool stored ion beams with a mass-to-charge ratio m/q of 1 to 160 u/e. At the maximum ion energy of CSR, 300 keV, this corresponds to a cooling energy range of 1 to 163 eV. The electron cooler will improve the storage time and the emittance of stored ion beams significantly. In addition, electron-ion collisions with electron energies up to 1 keV (in the laboratory-frame) will be possible in order to perform electron-ion collision experiments with a wide range of atomic and molecular species. The two different operation modes of the CSR, cryogenic temperature (10 K) and room temperature, and the foreseen bakeout of the vacuum system at ~550 K, impose high requirements on the design of the cooler.

Electrons are extracted from a cold GaAs photocathode which has been used at the Test Storage Ring already. The electron beam with low (~10 K) internal temperature is then guided by a relatively weak longitudinal magnetic field (up to 150 G in the interaction region and 250 G in the external electron beam transfer sections) into the CSR cryostat, merged with the ion beam and finally dumped outside of the cryostat at an electron collector. The magnetic system will consist of water-cooled copper coils operated at room temperature and, within the cryostat, of High Temperature Superconductors cooled by their own neon cooling system. The design and status of the CSR electron cooler will be presented.

74 ESD 2013 Contributed Poster No 25 C 25

Gas-phase spectroscopy of heme ions

J.A. Wyer1 and S. Brøndsted Nielsen1

1 Department of Physics and Astronomy, Aarhus University, Denmark

E-mail: [email protected]

The electronic structure of a biochromophore (i.e. light absorber) is strongly perturbed by its surrounding environment, e.g. water or amino acid residues within protein pockets or crevices. To reveal the intrinsic electronic properties, it is therefore necessary to study isolated molecules in vacuo. Many biochromophores are ionic in their natural environment, which renders experiments complicated as it is not possible to produce enough absorbing species for traditional light transmission spectroscopy. In Aarhus we have developed state-of-the-art apparatus to record gas-phase absorption spectra of macromolecular ions. The technique is based on the combination of an electrospray ion source, a multipole ion trap for pre-storage, an electrostatic ion storage ring or single pass setup, and pulsed tuneable lasers and relies on measurements of the delayed dissociation of photoexcited ions (action spectroscopy). It is also possible to build up the microenvironment of the ions to elucidate the impact of single molecules on an ions electronic structure. Such information is important in bioanalytical spectroscopy and for monitoring conformational changes and dynamics. Furthermore, our spectra provide a natural testing ground for future quantum chemical theories and methods.

Heme containing proteins are ubiquitous in nature and are responsible for key biological processes, such as oxygen transport and storage. Heme is a porphyrin with an iron atom located in the centre bound to four ring nitrogens. It colours blood red and is located in hydrophobic pockets of heme proteins with minimal access to water. Here, our recent spectroscopic measurements of heme ions will be presented, including our latest results which show how nitric oxide (NO) perturbs the absorption bands. Interactions with NO are particularly interesting as heme-NO proteins play a key role in many physiological functions, for example blood clotting and vasodilation upon the bite of blood-sucking insects.

References [1] M.K. Lykkegaard, A. Ehlerding, P. Hvelplund, U. Kadhane, M.-B.S. Kirketerp, S. Brøndsted Nielsen, S. Panja, J.A. Wyer, and H. Zettergren, J. Am. Chem. Soc., 130, 11856 (2008). [2] M.K. Lykkegaard, H. Zettergren, M.-B. S. Kirketerp, A. Ehlerding, J.A. Wyer, U. Kadhane, and S. Brøndsted Nielsen, J. Phys. Chem. A, 113, 1440 (2009). [3] J.A. Wyer and S. Brøndsted Nielsen, J. Chem. Phys., 133, 084306 (2010). [4] K. Støchkel, J.A. Wyer, M.-B.S. Kirketerp and S. Brøndsted Nielsen, J. Am. Soc. Mass Spectrom., 21, 1884-1888 (2010). [5] J.A. Wyer, C.S. Jensen, and S. Brøndsted Nielsen, Int. J. Mass Spectrom., 308, 126-132 (2011). [6] J.A. Wyer, and S. Brøndsted Nielsen, Angew. Chem. Int. Ed., 51, 10256-10260 (2012).

75 76 ESD 2013 - Participants

John Alexander Anastasia V. Bochenkova University of Stockholm University of Aarhus Sweden Denmark [email protected] [email protected]

Lars Henrik Andersen Richard Brédy University of Aarhus Université Lyon 1 Denmark France [email protected] [email protected]

Rodolphe Antoine Christian Breitenfeldt Université Lyon 1 and CNRS Universität Greifswald France Germany [email protected] [email protected]

Frank Arnold Henrik Cederquist MPI für Kernphysik, Heidelberg University of Stockholm Germany Sweden [email protected] [email protected]

Toshiyuki Azuma Vijayanand Chandrasekaran RIKEN Institute, Wako, Saitama Weizmann Institute, Rehovot Japan Israel [email protected] [email protected]

Erik Bäckström Li Chen University of Stockholm Université Lyon 1 Sweden France [email protected] [email protected]

Arno Becker Robert E. Continetti MPI für Kernphysik, Heidelberg University of California, San Diego Germany USA [email protected] [email protected]

Louise Belshaw Yoshinori Enomoto University of Belfast RIKEN Institute, Wako, Saitama United Kingdom Japan [email protected] [email protected]

Jérôme Bernard Andreas Fleischmann Université Lyon 1 Universität Heidelberg France Germany [email protected] [email protected]

Thorsten Best Michael Gatchell Universität Innsbruck University of Stockholm Austria Sweden [email protected] [email protected]

Klaus Blaum Sebastian George MPI für Kernphysik, Heidelberg MPI für Kernphysik, Heidelberg Germany Germany [email protected] [email protected] 77 Mohammad Gharaibeh Thomas Kolling Jordan University of Science and Technology Universität Kaiserslautern Jordan Germany [email protected] [email protected]

Mohamed El Ghazaly Claude Krantz King Abdulaziz City for Science and Technology MPI für Kernphysik, Heidelberg (KACST) Germany Saudi Arabia [email protected] [email protected]

Dmitry Grinfeld Holger Kreckel Thermo Fischer Scientific, Bremen MPI für Kernphysik, Heidelberg Germany Germany [email protected] [email protected]

Florian Grussie Michael Lange MPI für Kernphysik, Heidelberg MPI für Kernphysik, Heidelberg Germany Germany [email protected] [email protected]

Robert von Hahn Mats Larsson MPI für Kernphysik, Heidelberg University of Stockholm Germany Sweden [email protected] [email protected]

Michael Hass Sven Mannervik Weizmann Institute, Rehovot University of Stockholm Israel Sweden [email protected] [email protected]

Oded Heber Serge Martin Weizmann Institute, Rehovot Université Lyon 1 Israel France [email protected] [email protected]

Philipp Herwig Jun Matsumoto MPI für Kernphysik, Heidelberg Tokyo Metropolitan University Germany Japan [email protected] [email protected]

Mingchao Ji Sebastian Menk Université Lyon 1 MPI für Kernphysik, Heidelberg France Germany [email protected] [email protected]

Christopher Johnson Robert Moshammer Yale University MPI für Kernphysik, Heidelberg USA Germany [email protected] [email protected]

Hjalte Kiefer Yuji Nakano University of Aarhus RIKEN Institute, Wako, Saitama Denmark Japan [email protected] [email protected] 78 Lisbeth Munksgaard Nielsen Marco Rosenbusch University of Aarhus Universität Greifswald Denmark Germany [email protected] [email protected]

Oldřich Novotný Hilel Rubinstein Columbia University Weizmann Institute, Rehovot USA Israel [email protected] [email protected]

Aodh O’Connor Daniel Wolf Savin MPI für Kernphysik, Heidelberg Columbia University Germany USA [email protected] [email protected]

Céline Ortega Stefan Schippers University of Lyon 1 Universität Gießen France Germany [email protected] [email protected]

Henrik B. Pedersen Thomas Schlathölter University of Aarhus University of Groningen Denmark The Netherlands [email protected] [email protected]

Thomas Pfeifer Henning Schmidt MPI für Kernphysik, Heidelberg University of Stockholm Germany Sweden [email protected] [email protected]

Aneesh Prabhakaran Claus-Dieter Schröter Weizmann Institute, Rehovot MPI für Kernphysik, Heidelberg Israel Germany [email protected] [email protected]

Alexander Prygarin Dirk Schwalm Weizmann Institute, Rehovot MPI für Kernphysik, Heidelberg Israel Germany [email protected] [email protected]

Roland Repnow Haruo Shiromaru MPI für Kernphysik, Heidelberg Tokyo Metropolitan University Germany Japan [email protected] [email protected]

Christoph Riehn Ansgar Simonsson Universität Kaiserslautern University of Stockholm Germany Sweden [email protected] [email protected]

Stefan Rosén Kaija Spruck University of Stockholm Universität Gießen Sweden Germany [email protected] [email protected]

79 Kurt Ernst Stiebing Roland Wester Universität Frankfurt Universität Innsbruck Germany Austria [email protected] [email protected]

Kristian Støchkel Frank Wienholtz University of Aarhus Universität Greifswald Denmark Germany [email protected] [email protected]

Mark Stockett Andreas Wolf University of Stockholm MPI für Kernhpysik, Heidelberg Sweden Germany [email protected] [email protected]

Tetsumi Tanabe Jean A. Wyer KEK, Tsukuba University of Aarhus Japan Denmark [email protected] [email protected]

Richard Thomas Daniel Zajfman University of Stockholm Weizmann Institute, Rehovot Sweden Israel [email protected] [email protected]

Yoni Toker Weizmann Institute, Rehovot Israel [email protected]

Matthias Tombers Universität Kaiserslautern Germany [email protected]

Oliver Trapp Universität Heidelberg Germany [email protected]

Xavier Urbain UCL, Louvain-la-Neuve Belgium [email protected]

Sergey Vaintraub Weizmann Institute, Rehovot Israel [email protected]

Stephen Vogel MPI für Kernphysik, Heidelberg Germany [email protected]

80