Abstract Number: D1/1-01

COLLABORATIVE STUDIES OF PROTON INDUCED MULTIPLE IONIZATION AND EMISSION RESULTING FROM DRESSED ION IMPACT

Robert Dubois

Missouri University of Science and Technology, Rolla, USA [email protected]

During a several decade collaboration between S.T. Manson and R.D. DuBois and coworkers, a series of papers concerned with multiple ionization mechanisms in proton-atom collisions and with electron emission resulting from dressed ion impact were published. This talk will briefly discuss the major findings of these studies.

Abstract Number: D1/2-02

SPECTROSCOPY AND DYNAMICS OF RARE-GAS ATOMS IN THE HARD X-RAY DOMAIN

Maria Piancastelli

Uppsala University, Uppsala, Sweden maria-novella.piancastelli@.uu.se

Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement, LCPMR, Paris, France and Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden

The possibility of conducting hard x-ray photoexcitation and photoionization experiments under state-of-the art conditions in terms of and electron kinetic energy resolution has become available only in the last few years at selected synchrotron radiation facilities, in particular at the GALAXIES beam line operational at the French synchrotron SOLEIL.

Some significant examples of recent developments in spectroscopy and dynamics of isolated atoms in the hard x-ray regime will be presented, including recoil phenomena, post-collision interaction effects, double-core-hole formation, and nonstatistical ratio of spin-orbit split components (the latter in collaboration with S.T.Manson).

Abstract Number: D1/3-03

A STUDY OF THE NEAR THRESHOLD REGION FOR DOUBLE PHOTOIONIZATION OF ATOMIC OXYGEN Wayne Stolte

Lawrence Berkeley National Laboratory, USA [email protected]

A joint experimental and theoretical investigation on oxygen double photoionization — the emission of two from atomic oxygen following single photon absorption. High- resolution experimental measurements were performed at the Advanced Light Source, revealing sharp resonance structure superimposed on the more familiar Wannier-like, nearly-linear back- ground. These resonance features are attributed to ionization-plus-excitation Feshbach-resonances embedded in the double ionization continuum.

Abstract Number: D1/4-04

K-SHELL FLUORESCENCE YIELD AND PHOTOABSORPTION CALCULATIONS*

M. Fatih Hasoglu

Hasan Kalyoncu University, Turkey [email protected]

Fluorescence yields are important for determining charge-state distributions following K-shell excitation and/or ionization, as is the competing Auger yield. We have shown that the inclusion of higher-order effects often gives results that differ considerably from the commonly-used data, highlighting the inadequacy of the commonly-used configuration-averaged approximation, and providing more reliable data for astrophysical plasma modeling.

K-shell photoabsorption calculations are equally as important for a variety of astrophysical processes, in particular, for determining the elemental abundances in the interstellar medium (ISM) from observed X-ray absorption spectra. Photoabsorption cross sections for the isonuclear C - C3+ ions were computed and compared to experimental 1s → 2p, 3p. These benchmarked cross sections were then used to model the Chandra X-ray absorption spectrum of the blazar Mkn 421 near the carbon K-edge, thereby obtaining instrumental and interstellar carbon ion abundances. Ongoing work on neutral and ionic Si, and the latest interpretations for silicon abundance in the ISM, will be discussed.

*In addition to their coauthorship of ten refereed publications over the past fifteen years, Steven Manson mentored M. Fatih Hasoglu as an external doctoral thesis committee member and then as a postdoctoral research advisor.

Abstract Number: D1/5-05

COINCIDENCE PHOTOELECTRON MEASUREMENTS FOLLOWING 2P PHOTOIONIZATION IN MG

Emma Sokell

University College Dublin, Ireland [email protected]

Coincidence measurements, where the photoelectron and the Auger electron arising from the creation and decay of a 2p3/2 vacancy are detected in coincidence, have been carried out at a range of photon energies above the 2p photoionization threshold in magnesium. Triple differential cross- section (TDCS) measurements were made, by determining both the energy and the angle of emission of the two electrons. Three TDCS measurements were obtained at each of the photon energies investigated and these data fit simultaneously using the two-step model presented by Schmidt [1]. The fitting provided information about the dipole matrix elements for the process, which were compared with the results of Relativistic Random Phase Approximation calculations for all of the photon energies studied. [1] Schmidt V 1997 Electron Spectrometry of Atoms using Synchrotron Radiation, Cambridge Monographs on Atomic, Molecular and Chemical Physics. Cambridge University Press.

Abstract Number: D1/6-06

FROM NON-DIPOLE EFFECTS TO ELECTRON-ION COINCIDENCE SPECTROSCOPY

Daniel Rolles

Kansas State University, Manhattan, USA [email protected]

Abstract will be added shortly

Abstract Number: D1/7-07

RESONANT INNER-SHELL EXCITATION DRIVES NUCLEAR DYNAMICS IN CYCLOPROPANE

Stacey Sorensen

Lund University, Sweden [email protected]

Selective excitation of valence states near the carbon 1s ionization threshold in the cyclic (triangular) cyclopropane molecule leads to an evolution of the cyclic structure which depends upon the nature of the core-excited state. The experimental data is presented and preliminary calculations support interpretation of the coincidence ion-imaging data.

Abstract Number: D2/1-08

ENERGY AND TIME RESOLUTION IN ATOMIC PROCESSES

A. Ravi P. Rau

Louisiana State University, USA [email protected]

Quantum physics brought to the fore a conjugate relationship between energy and time in physical systems and phenomena. They afford alternative representations of the same physics. Both experimental observation and theoretical calculation can work with either high energy resolution or very short time-scale treatment, technology often the determinant on what is feasible or convenient. Examples in photoabsorption in atoms over the last sixty years of Steve Manson's contributions to the field will be discussed.

Abstract Number: D2/2-09

FANO LINESHAPE PHYSICS IN THE TIME DOMAIN

Chris Greene

Purdue University [email protected]

The renowned Fano lineshape that arises when a bound state is coupled to a continuum can display an asymmetrical profile when an observable is plotted versus frequency or energy Such lineshapes are often referred to as "Fano profiles", where the asymmetry is controlled by a parameter q in the standard notation used for the energy dependence. What is less familiar is that excitation of such a resonance by a very fast and short pulse can induce an oscillating dipole moment whose phase exhibits a very simple dependence on the Fano lineshape asymmetry parameter q. This talk will discuss the physics behind this simple relationship, and its experimental observation by Christian Ott, Thomas Pfeifer, and their collaborators in laser excitation processes in atomic helium.

Abstract Number: D2/3-10

GENERATION OF GIGAWATT ISOLATED ATTOSECOND PULSES BY HIGH-ENERGY OPTICAL WAVEFORM SYNTHESIZE

Katsumi Midorikawa

RIKEN Tokyo, Japan [email protected]

By innovatively introducing multicycle pulse synthesis strategy and combining the waveform synthesizer and the loose-focusing method for HHG, a shot-to-shot- reproducible high-energy XUV continuum supporting the generation of isolated attosecond pulses is achieved. The peak power of this continuum is evaluated to be beyond 1 GW with a170-as transform limit duration. We also discuss the extension of this scheme for generating high-energy isolated attosecond pulses beyond the carbon K-edge.

Abstract Number: D2/4-11

PHOTOINDUCED ULTRAFAST PROCESSES IN ATOMS AND FULLERENES

Himadri Chakraborty

Northwest Missouri State University [email protected]

The talk will begin highlighting Steve Manson’s contributions in the domain of attosecond time- delay studies in the field of photoionization of confined atoms based on the framework of the classic Wigner-Smith formalism. The discussions will then drive into the domain of our group’s research in the same topic while applying different formalisms and modelling. A link between the two domains will be my longtime collaboration with Steve. The second part of the talk will focus on the ultrafast electron-phonon coupled relaxation dynamics following surgical photoexcitations in atomic endofullerene molecules. Such nonadiabatic relaxation is a key process in organic photovoltaics, whose donor-acceptor complexes predominantly base on fullerene materials. I will present some selected recent results on the charge transfer forming non-local excitons within these molecules and a novel phenomenon of transient electron trapping along the decay path.

Abstract Number: D2/5-12

USING CIRCULAR DICHROISM TO CONTROL ENERGY TRANSFER IN MULTI-PHOTON IONIZATION

Klaus Bartschat

Drake University, Des Moines, Iowa, USA [email protected]

Chirality causes symmetry breaks in a large variety of natural phenomena ranging from particle physics to biochemistry. I will report on a joint experimental and theoretical project [1], in which we investigate one of the simplest conceivable chiral systems, a laser-excited, oriented Li target. Prepared in a polarized (2p, m=+1) state in an optical trap, the atoms are exposed to co- and counter-rotating circularly polarized femtosecond laser pulses. For a field frequency near the excitation energy of the oriented initial state, a strong circular dichroism is observed, and the photoelectron energies are significantly affected by the helicity-dependent Autler-Townes splitting. Besides its fundamental relevance, this system is suited to create spin-polarized electron pulses with a reversible switch on a femtosecond timescale at an energy resolution of a few meV.

[1] A. H. N. C. De Silva, D. Atri-Schuller, S. Dubey, B. P. Acharya, K. L. Romans, K. Foster, O. Russ, K. Compton, C. Rischbieter, N. Douguet, K. Bartschat, and D. Fischer, https://arxiv.org/abs/2006.07408

Abstract Number: D2/6-13

WIGNER TIME DELAY IN PHOTODETACHMENT OF NEGATIVE IONS

Sourav Banerjee

IIT Madras, Chennai, India [email protected]

Advancements in the field of ultrafast laser technology have stimulated many insightful investigations toward understanding electron dynamics in atoms on attoseconds time scale. The importance of studying time delay in photodetachment from negative ions comes from its ability to reveal important correlation effects, especially since time delay results in such systems are not eclipsed by the long range Coulomb potential as in photoionization of neutral atoms. This study reports a few results of Wigner time delay in photodetachment of negativeions in a few cases using alternative relativistic many body approximations.

Abstract Number: D2/7-14

ATTOSECOND SOFT-X-RAY SPECTROSCOPY IN THE GAS AND LIQUID PHASES

Hans Jakob Worner

ETH, Zurich, Switzerland [email protected]

In the first part of this talk, I will discuss time-resolved X-ray spectroscopy based on high-harmonic generation. Our group has recently demonstrated the potential of table-top X-ray absorption spectroscopy with a water-window high-harmonic source, observing the temporal evolution of unoccupied molecular orbitals, as well as molecular shape resonances during chemical reactions [1]. Compressing the mid-infrared driving pulses to less than 2 optical cycles, we have demonstrated the extension of this table-top source to fully cover the oxygen K-edge with fluxes sufficient for time-resolved measurements [2]. Using the same technique, we have also demonstrated the generation of isolated attosecond pulses, which have established a new record of the shortest light pulses ever measured (43 attoseconds) [3]. We have used attosecond spectroscopy at the carbon K-edge to measure the D1D0 relaxation of the ethylene cation, which occurs in 6.8±0.2 fs, representing the fastest conical-intersection dynamics measured to date. Using attosecond spectroscopy at the silicon L2,3-edge, we have observed the decay and revival of a 1.32-1.38-fs electronic wave packet in neutral silane, driven by both nuclear and non-adiabatic dynamics.

The second part of this talk will cover attosecond time-resolved photoelectron spectroscopy, and in particular its extension from molecules [4] to liquids [5], reporting on photoemission delays of liquid compared to gaseous water. The measured time delays range from 50-70 attoseconds and are shown to mainly originate from the solvation of water molecules, with liquid-phase electron scattering playing a minor role. This conclusion is quantitatively supported by complementary measurements of photoionization time delays of size-resolved water clusters. These experiments reveal a direct link between the measured time delays and the first moment of the electron-hole density, i.e. the spatial extension of the created electron hole.

[1] Y. Pertot, C. Schmidt, M. Matthews, A. Chauvet, M. Huppert, V. Svoboda, A. von Conta, A. Tehlar, D. Baykusheva, J.-P. Wolf, H. J. Wörner, “Time-resolved X-ray absorption spectroscopy with a water-window high-harmonic source”, Science 355, 264 (2017) [2] C. Schmidt, Y. Pertot, T. Balciunas, K. Zinchenko, M. Matthews, H. J. Wörner, J.-P. Wolf, “High-order harmonic source spanning up to the oxygen K-edge based on filamentation pulse compression”, Opt. Exp. 26, 11834 (2018) [3] T. Gaumnitz, A. Jain, Y. Pertot, M. Huppert, I. Jordan, F. Ardana-Lamas, H. J. Wörner, “Streaking of 43-attosecond soft-X-ray pulses generated by a passively CEP-stable mid-infrared driver”, Opt. Exp. 25, 27506 (2017) [4] M. Huppert, I. Jordan, D. Baykusheva, A. von Conta, H. J. Wörner, "Attosecond delays in molecular photoionization", Phys. Rev. Lett. 117, 093001 (2016) [5] Inga Jordan, Martin Huppert, Dominik Rattenbacher, Michael Peper, Denis Jelovina, Conaill Perry, Aaron von Conta, Axel Schild, Hans Jakob Wörner, “Attosecond spectroscopy of liquid water”, Science 369, 974 (2020)

Abstract Number: D2/8-15

ATTOSECOND DELAYS IN PHOTOEMISSION

Eva Lindroth

Stockholm University, Stockholm, Sweden [email protected]

The electron dynamics, during for example a photoionization process, is encoded in the amplitude and phase of the released electron wave packet. A key quantity is the spectral derivative of this phase, the group delay. It reflects the delay or advance of the electron when it travels through the atomic potential to eventually emerge in the continuum. Attosecond interferometric techniques have made such phase information available and there are still new surprises waiting when old favourites, such as photoionization of xenon above the 4d-threshold, are reinvestigated with the new techniques. I will discuss attosecond delays in laser-assisted photoionization with an emphasis on the theoretical treatment, the influence of the “second” photon, spin and many-body effects.

Abstract Number: D3/1-16

FURTHER THOUGHTS ON RESONANCES IN CONFINED ATOMS AND IONS

Jean-Patrick Connerade

Imperial College London, UK and European Academy (EASAL) Paris, France [email protected]

A new type of resonance in a confined atomic system is proposed. It would migrate strongly in energy as a function of the degree of confinement, moving up or down in the Rydberg manifold according to the properties of the confining shell.

Confined atoms are rich in new effects of which some remain to be discovered. They offer new insights into atomic physics. Experimentally, the observations are very challenging, but some quite simple theory can already be advanced. Thus, in a paper with Dolmatov and Manson, we have distinguished between three types of resonance which can occur, viz. (a) those due to the atom, modified by confinement, (b) resonances due to the confining potential, modified by the presence of the confined atom and (c) resonances of molecular origin. In the present paper, I would like to suggest yet a fourth situation. Whereas (a), (b) and (c) is a general distinction for confined atoms, because spherical confinement necessarily produces confinement resonances, the new type of resonance I will describe in the present note is of a unique kind, because it is a rare one. It can only occur for rather specific atoms or ions.

In the case considered here, it becomes necessary to examine the full excitation channel, viz. a complete Rydberg series, rather than simply a single atomic state. The atoms involved are those with a near-critical double-well effective potential.

Abstract Number: D3/2-17

HOW A SIMPLE MODEL CAN PUSH THE DEVELOPMENT OF THE FIELD: FROM ABSTRACTLY CONFINED ATOMS TO AN AD HOC STUDIES OF FULLERENES

Valeriy Dolmatov

University of North Alabama, Florence, USA [email protected]

In this brief review, the author summarizes the most remarkable from his point of view results of studies on confined atoms that exemplify how a simple, even over-simplified physical modelling of a system may become one of the leading theories in the development of the field. The model the author has in mind is the approximation of the surrounding an atom environment by a spherical square-well (in the radial coordinate) potential with either the infinite repulsive walls or both the finite repulsive and attracted walls. Selected results obtained in the framework of this model on the restructuring of atoms under pressure as well as the spectra and structure of atoms confined inside CN fullerenes are presented along with the underlining of the role they have played in the world of confined atoms studies. Given the special status of the conference – in honor of Prof. Dr. Steven Trenton Manson’s impact on the field of atomic and molecular physics - the selected studies include overwhelmingly those (but not limited to) where the celebrated person has contributed a lot to.

Abstract Number: D3/3-18

PROBING MOLECULAR DYNAMICS IN REAL TIME FROM WITHIN WITH FREE ELECTRON

Nora Berrah

University of Connecticut, Storrs, USA [email protected]

The knowledge of the earliest time dynamics in molecular photophysics and photochemistry are critical because their role is to harness the energy from , initiating electronic and nuclear motion which is fundamental in many areas of science. Our ultimate goal is to understand the coupled electronic and nuclear dynamics induced by the absorption of photons by molecules, which leads first to attosecond electron excitation within the molecules, followed by nuclear motion in the femtosecond range. This eventually results in the breaking and making of chemical bonds on the picosecond timescale. The past decade has seen the exciting birth of the first X-ray laser, the LCLS free electron laser (FEL) followed by other FELs around the world, leading to an explosion of new science, in the femtosecond and very recently in the attosecond regime. I will present our recent time- resolved experimental results using pump-probe technique with FELs to watch, in real time, the response of large molecules to intense X-rays as well as to examine the role of physical and chemical effects and how they lead to the timing of bonds breaking and bond forming. This work was funded by the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, US Department of Energy, grant No. DE- SC0012376

Abstract Number: D3/4-19

EXPERIMENTAL STUDIES ON PHOTOABSORPTION BY ENDOHEDRAL FULLERENE IONS

Alfred Müller

Giessen University, Germany [email protected]

While atoms confined in fullerene cages have been addressed by numerous theoretical approaches, experimental attempts to understand the behavior of encaged atoms have been scarce. The main reason for the lack of experiments is the limited availability of endohedral fullerene materials and the difficulty to produce them in sizable quantities. The most direct access to confined atoms is the observation of their response to irradiation by photons. Targets for photoabsorption measurements can be provided by evaporating endohedral fullerene powders which requires very clean sample materials. An alternative experimental approach is the exposure of mass- and charge- selected endohedral fullerene ions to photon beams in a merged- beams arrangement. This scheme permits the observation of different final ionic products resulting from photoionization and photofragmentation of the target species. Mass-spectrometrically purified beams of endohedral fullerene ions of Xe@C 60 , Ce@C 82 , Sc 3 N@C 80 , and Lu 3 N@C 80 were merged with intense beams of synchrotron radiation at energies near inner-shell absorption edges of the atomic constituents. Photoions A@C n q+ (with different final charge states q of the product ions, numbers n of carbon atoms left in the cage, and the encapsulated moiety A) resulting after the absorption of an energetic single photon were recorded as a function of photon energy and cross sections were determined. A particularly interesting result of such measurements is the clear observation of confinement resonances for Xe@C 60 , where a Xe atom is centrally confined in a fullerene sphere.

Abstract Number: D3/5-20

STUDY OF CORRELATION EFFECTS IN GROUND AND EXCITED STATES OF A@C60: ANALYSIS EMPLOYING SHANNON ENTROPY AND COULOMB CONFINEMENT RESONANCES

Jobin Jose

IIT Patna, Bihta, Bihar, India [email protected]

It is well understood that the many-electron correlation effects have a decisive role on the electronic structure and dynamics of endohedral systems (A@C60) [1]. The objective of the present work is two-fold; the first focus is to present Shannon entropy [2] as an indicator of correlation effects in endohedral atoms. The second objective is to investigate the Coulomb confinement resonances (CCR) [3] in Ar endohedrally confined in anionic fullerenes. In accomplishing the later objective, emphasis is given to the effect of interchannel coupling of CCR on the photoionization dynamics. The endohedral environment is approximated as an atom trapped in an attractive spherically symmetric potential, employing two models: (A) hard Annular SquareWell (ASW) and (B) smooth Gaussian annular square well (GASW).

References [1] V. K. Dolmatov, A. S. Baltenkov, J. P. Connerade and S. T. Manson, Radiat. Phys. Chem. 70 417(2004). [2] C. E. Shannon, A mathematical theory of communication, Bell Syst. Tech. J. 27, 379 (1948).

Abstract Number: D3/6-21

NUMERICAL SIMULATIONS OF STORAGE AND THERMOMETRY OF IONS IN A 16-POLE ION TRAP AND A 16-WIRE ION TRAP

S. Sunil Kumar

IISER , Tirupati, India [email protected]

22-pole radiofrequency ion traps are routinely used in a variety of applications such as spec troscopy, ion-molecule reations, and laser-induced reactions [1, 2, 3]. Conventional design of the ion trap restricts the access of the ions along the axis of the trap only. This in turn limits the application of such traps. An alternative design employs thin wires instead of rods for radial confinement of the ions. Even though the trapping and storage efficiency of the ions is slightly compromized with the new design, it opens up a wide range of experiments that can be performed with the trap such as absolute photodetachment cross-section measurements [4] and fluorescence spectroscopy. In this work, we numerically simulate the storage of the ions within a 16-pole ion trap and a 16-wire ion trap and compare the thermometry of the ions in the two devices. References [1] D. Gerlich, in Advances in Chemical Physics 1–176 (John Wiley & Sons, Inc., 1992) [2] S. Br¨unken, L. Kluge, A. Stoffels, J. P´erez-R´ıos, & S. Schlemmer, J. Mol. Spectrosc. 332, 67 (2017) [3] S. S. Kumar, F. Grussie, Y. V. Suleimanov, H. Guo, & H. Kreckel, Sci Adv 4, eaar3417 (2018) [4] S. S. Kumar, D. Hauser, R. Jindra, T. Best, S. Rouˇcka, W. D. Geppert, T. J. Millar, and R. ˇ Wester, ApJ 776, 25 (2013)

Abstract Number: D3/7-22

FROM MODELS TO FULL MOLECULAR CALCULATIONS

Piero deCleva

University of Trieste, Italy [email protected]

A large class of confined systems is encapsulated atoms or small molecules in a host environment provided by a larger system, e.g. cavities in macromolecules, zeolites, etc. These are often important as active centers for catalysis and chemical reactions, and in general properties of the guest systems are modified and can be tuned by the host. A special system that has received a lot of attention, especially theoretically because of the relatively easy way of describing it with spherical models, is the class of endohedral fullerenes, where mostly single atoms, Figure 1. Snapshots of the continuum T1 orbital in but now also small molecules, can be photoionization of Ca 1s → T1 in Ca@C60 for confined in the quasi spherical C60 cage increasing energy. From [5]. (or higher fullerenes).

Here we shall consider some results relative to photoionization of endohedral fullerenes, based on fully molecular calculations, avoiding the modelling of the C60 cage as a spherical potential shell, which although capturing many important effects neglects the role of atomic cores, which affect for instance the delocalization and mobility of the cage electrons, which are more tightly kept in place by the chemical bonds, and the scattering of hard cores on electrons coming from the guest atom (Figure 1). Our theoretical approach is based on the accurate solution of bound and continuum orbitals in a general molecular potential via expansion in a multicenter B-spline basis, at the DFT and

TDDFT levels [1-3]. We shall review results for free C60 [4], endohedral atomic systems [5,6] and a first results of a current study of an encapsulated molecule, N2@C60. References [1] H. Bachau, E. Cormier, P. Decleva, J. E. Hansen and F. Martin, Reports on Progress in Physics, 64, 1815 (2001). [2] D. Toffoli, M. Stener, G. Fronzoni and P. Decleva, Chem. Phys.,276, 25 (2002) [3] M. Stener, G. Fronzoni, and P. Decleva, J. Chem. Phys., 122 (2005) 234301 [4] A. Ponzi, S. T. Manson and P.Decleva, J. Phys. Chem. A 124 (2020) 108 [5] M. Stener, G. Fronzoni, D. Toffoli, P. Colavita, S. Furlan and P. Decleva, J. Phys. B: At. Mol. Opt. Phys., 35, 1421 (2002) [6] A. Ponzi, P. Decleva and S.T. Manson, Phys. Rev. A 92 (2015) 0234

Abstract Number: D4/1-23

INTERACTION OF SHORT WAVELENGTH PHOTONS WITH ATOMIC AND MOLECULAR IONS: SOME EXAMPLES.

Eugene Kennedy

Dublin City University, Ireland [email protected]

Studies of the interaction of short wavelength photons with atomic or molecular positively charged ions remain challenging, both experimentally and theoretically. Experiments provide key data for the interpretation of fundamental processes in laboratory and astrophysical plasmas and for benchmarking advanced theoretical calculations taking account of inner-shell and/or multi- electron excitations. Atomic or molecular ions can provide a “laboratory” to investigate the interplay between many-body electron-electron correlations, electron-nucleus interactions, and relativistic effects by systematically looking at changes along ionic sequences.

Photoionisation experiments on ions require appropriately bright short wavelength light sources combined with sufficiently intense ion beams. Considerable progress has been made over the past three or four decades in investigating inner-shell photoionization cross sections for atomic ions. In contrast, studies in molecular ions are still in their infancy and the systematic study of their photoionization behaviour remains a largely unexplored field of research.

This short talk provides a) some examples of combined experimental and theoretical atomic ion studies based on laser-produced plasmas as backlighting continuum sources and synchronized laser plasma plumes providing the absorbing ion species, while highlighting the advantages and disadvantages of this approach and b) the results of more recent complementary laboratory and theoretical investigations of ions based on experiments with the photon-ion merged beam apparatus on the Pleiades beamline at the French synchrotron Soleil facility.

The merged beam approach allows photoionisation absolute cross sections for atomic ions to be determined and also enables investigations of molecular ions. Examples of molecular hydride ions in the K- and L-shell spectral regions, and comparisons with their atomic ion counterparts, are presented [1-4].

References 1) Mosnier J-P et al Phys. Rev. A 93, 061401(R) (2016) 2) Kennedy E T et al Phys. Rev. A 97, 043410 (2018) 3) Kennedy E T et al IOP Conf. Series: Journal of Physics: Conf. Series 1289, 012003 (2019) 4) Carniato S et al Atoms 8, 67 (2020)

Abstract Number: D4/2-24

BREIT INTERACTION EFFECTS ON RECOMBINATION PROCESSES OF HIGHLY CHARGED IONS

Nobuyuki Nakamura

The University of Electro-Communications, Tokyo, Japan [email protected]

The Breit interaction is a relativistic effect in the electron-electron interaction potential; it is thus generally important for highly charged heavy ions. However, in the calculation of the energy levels for heavy ions, the Breit interaction is still a small perturbation compared with the main Coulomb term. On the other hand, it has been found that the Breit interaction can make a strong contribution to the dynamics of highly charged heavy ions. This talk briefly reviews significant Breit interaction effects on dielectronic recombination processes of highly charged heavy ions.

Abstract Number: D4/3-25

MEASUREMENTS OF ACTIVE REGION MAGNETIC FIELD OF THE SOLAR CORONA USING SPECTRAL LINES OF FE X

Roger Hutton

Fudan University, Shanghai, China [email protected]

This contribution illustrates the potential of a new diagnostic technique that allows the measurement of the coronal magnetic field strength in solar active regions utilizing a handful of bright Fe x and Fe xi lines commonly observed by the Hinode/EIS high resolution spectrometer. The importance of this new diagnostic technique lies in two basic facts: 1) the coronal magnetic field is probably the most important quantity in coronal physics, as it is at the heart of the processes regulating Space Weather and the properties of the solar corona, and 2) this technique can be applied to the existing EIS archive spanning from 2007 to 2020, including more than one full solar cycle and covering a large number of active regions, flares, and even coronal mass ejections. This new diagnostic technique opens the door to a whole new field of studies, complementing the magnetic field measurements from the upcoming DKIST and UCoMP ground based observatories, and extending our reach to active regions observed on the disk and until now only sampled by radio measurements.

Abstract Number: D4/4-26

COMPLEX PHOTORECOMBINATION AND LINE FORMATION IN HIGHLY CHARGED IONS

José R. Crespo López-Urrutia

Max-Planck-Institut für Kernphysik, Heidelberg, Germany [email protected].

Dielectronic recombination dominates the photorecombination process in a wide range of plasma conditions. Configuration interaction in semi-filled shells of astrophysically abundant elements such as Fe also gives rise to a multitude of resonant photorecombination channels [1] that strongly affects both plasma ionization balance and contributes to X-ray emission [2] and polarization [3,4]. Experiments with electron beam ion traps can help surveying such photon emission processes by sampling spectra information on the different decay pathways both under photorecombination and photoexcitation conditions. These data are essential for the understanding and quantitative analysis [5] of astrophysical X-ray observations from operating and upcoming space observatories.

[1] C. Beilmann et al., Phys. Rev. Lett. 107, 143201 (2011) [2] C. Shah et al., Astrophys. Jour. 881, 100 (2019) [3] C. Shah et al., Astrophys. Jour. Suppl. Series 234, 27 (2018) [4] C. Shah et al., Phys. Rev. E 93, 061201(R) (2016) [5] L. Gu et al., Astron. & Astrophys. 641, A93 (2020)

Abstract Number: D4/5-27

ELECTRON EMISSION FROM IODOURACIL AND RADIO- SENSITIZING EFFECT

Lokesh C. Tribedi

TIFR, Mumbai, India [email protected]

Availability of high energy electron heavy ion beams and e-spectroscopy technique have not only widened the scope of the basic AM science research but also helped in various applications including hadron-therapy. Hadron therapy combined with nanotechnology has been proposed to be an elegant alternative for cancer treatment. Internal amplification of e-emission causing radio- biological effectiveness in nano-inserted biomolecules is of prime importance and has been measured here for iodouracil. We will discuss our recent results on the enhancement in the e- emission cross sections for iodouracil under the influence of fast carbon-ions. The e-emission from iodouracil is substantially enhanced over uracil and water. The enhancement is much larger then the CDW-EIS model prediction. The sensitizing factor is explained in terms of atomic giant dipole resonance (GDR) of strongly correlated 4d-electrons in I-atom. Some of the recent references are given below [1-9]

References: 1. M. Roychowdhury, L.C. Tribedi et al. PRA 102, 012819 (2020) 2. M. Roychowdhury, L.C. Tribedi et al. J. Phys. B 53, 235201 (2020) 3. A. Mandal, L. C. Tribedi et al, PRA 101, 062708 (2020) 4. A. Mandal, L. C. Tribedi et al, PRA (accepted in press-2020) 5. S. Bhattacharjee and L C Tribedi et al EPJD 74, 163 (2020) 6. A. H. Kelkar and L. C. Tribedi et al EPJD 74, 157 (2020) 7. C. Bagdia, L. C. Tribedi et al (accepted, in press EPJD 2020) 8. L. C. Tribedi; Interdisciplinary Research on Particle Collisions and Quantitative Spectroscopy Vol-2 (World Scientific, 2019) Ch-3 9. A. V. Verkhovtsev et al. PRL 114, 063401 (2015)

Abstract Number: D4/6-28

MULTICONFIGURATION DIRAC-HARTREE-FOCK RADIATIVE PARAMETERS FOR EMISSION LINES IN CE II – IV IONS AND CERIUM OPACITY CALCULATIONS FOR KILONOVAE

Patrick Palmeri

Université de Mons, Belgium [email protected]

Large-scale calculations of atomic structures and radiative properties have been carried out for singly, doubly- and trebly ionized cerium. For this purpose, the purely relativistic multiconfiguration Dirac-Hartree-Fock (MCDHF) method was used, taking into account the effects of valence-valence and core-valence electronic correlations in detail. The results obtained were then used to calculate the expansion opacities characterizing the kilonovae observed as a result of neutron star mergers. Comparisons with previously published experimental and theoretical studies have shown that the results presented in this work are the most complete currently available, in terms of quantity and quality, concerning the atomic data and monochromatic opacities for Ce II, Ce III and Ce IV ions.

Abstract Number: D4/7-29

TESTING QED WITH THE FINE-STRUCTURE SPLITTING IN HIGHLY-CHARGED F-LIKE IONS

Yuri Ralchenko

NIST, USA [email protected]

Quantum electrodynamics (QED) is currently considered to be one of the most accurate theories of fundamental interactions. As its extraordinary precision offers unique scientific opportunities, e.g., search for new physics, stringent experimental tests of QED continue to be of high importance. To this end, highly charged ions represent an exceptional test-bed due to enhanced QED effects. Recently, forbidden transitions in F-like ions have been analyzed to few ppm precision, resolving previous discrepancies between theory and experiment. Here we further test the accuracy of QED calculations with three new (Re, Os, Ir), and two improved (Kr, W) measurements of the 2p1/2-2p3/2 transition energy in the ground configurations of F-like ions using the NIST electron-beam ion trap and extreme-ultraviolet and x-ray spectrometers. Good agreement between theoretical and experimental energies is found for all considered elements.

Abstract Number: D4/8-30

REDSHIFT OF THE ISOLATED ATOMIC EMISSION LINE IN DENSE PLASMA ENVIRONMENT

Tu-Nan Chang

University of Southern California, Los Angeles, USA [email protected]

By carefully examining the spatial and temporal criteria of the classical Maxwell-Boltzmann statistics based on the Debye-Hückel (HD) approximation1, together with the atomic structure calculation, both non-relativistic and relativistic, we have recently shown that the redshifts of the isolated emission lines of the H-like and He-like ions (with the nucleus charge Z approximately between 6 and 18) subject to outside dense plasma environment could be effectively estimated2. Based on the quasi-hydrogenic picture, we are able to show that the redshifts could be expressed in terms of a general expression as a function of the Debye length1 and, in turn, leading to the determination of the electronic density and the temperature of the dense plasma. We will also present the results of our estimated redshifts which are consistent with the most recent experimental measurements.3

1 P. Debye and E. Hückel, Physikalische Zeitschrift 24, 185 (1923). 2 T. N. Chang, T. K. Fang, and X. Gao, PRA 91, 063422 (2015); T. K. Fang, C. S. Wu, X. Gao, and T. N. Chang, PRA 96, 052502 (2017); T. K. Fang, C. S. Wu, X. Gao, and T. N. Chang, Phys. Plasmas 25, 102116 (2018). 3 C. R. Stillman et al, PRE 95, 063204 (2017); P. Beiersdorfer et al, PRA 100, 012511 (2019).

Abstract Number: D4/9-31

HIGH RESOLUTION MOMENTUM MEASUREMENTS- ITS MILESTONE CONTRIBUTIONS TO QUANTUM PHYSICS

Horst Schmidt-Böcking

Goethe-Universität, Frankfurt, Germany [email protected]

Abstract: Otto Stern is the pioneer of high resolution momentum measurements of atoms moving in vacuum. In 1919 he laid the foundations of his molecular beam method, with which he could prepare the transverse momentum of Ag atoms with sub-atomic precision. Stern and Gerlach applied in 1922 this method in their famous Stern-Gerlach experiment and achieved a transvers momentum resolution of 0.1 a.u. which corresponds to a transverse energy resolution of about 1 micro eV. This experiment provided the first direct evidence for angular momentum quantization in atoms. More than twenty later Nobel laureates used Sterns high resolution concept. Sterns apparatus was only about 10 cm long, but applying his method in traps the path-length is de-facto infinite and thus a resolution (e.g measuring masses by momentum measurement) approaches today 10 -13 . Since about 30 years Sterns method is extended to multi-particle coincidence measurements in single reactions (eg. by using the COLTRIMS Reaction Microscope C-Remi). Achieving for all charged fragments a momentum resolution below 10 -2 a.u. the entangled dynamics in such reactions can be visualized with atto- or even zepto-second resolution.

Abstract Number: D5/1-32

ATTOSECOND CHRONOSCOPY: FROM SIMPLE ATOMS TO COMPLEX SYSTEMS(*)

Joachim Burgdorfer

University of Vienna, Austria [email protected]

Recent advances in the generation of well-characterized sub-femtosecond laser pulses have opened up unprecedented opportunities for the real-time observation of electronic dynamics in atoms, molecules and solids. Such attosecond chronoscopy allows a novel look at a wide range of photophysical and photochemical processes in the time domain. Attosecond chronoscopy also raises fundamental conceptual questions as to which novel information can be accessed and which dynamical processes can be steered. Attosecond timing of photoemission is a prominent case in point. We will illustrate the potential and challenge with help of a few prototypical examples ranging from simple atoms and C_60 clusters to solid heterostructures and ultrafast currents in dielectrics.

(*): work in collaboration with I. Brezinova, S. Donsa, I. Floss, C. Lemell,R. Kienberger, F. Krausz, M. Schultze, X.M.Tong

Abstract Number: D5/2-33

ATTOSECONDS AND DIPOLE - REAL-TIME AB INITIO COMPUTATION OF SINGLE- AND TWO-PHOTON IONIZATION

K L Ishikawa

University of Tokyo, Japan [email protected]

This talk covers real-time ab initio computation of atomic single- and two-photon ionization by femtosecond extreme-ultraviolet pulses. We discuss the photoelectron angular distribution and its connection to the attosecond photoemission delay, our knowledge of which we owe much to Steve.

Abstract Number: D5/3-34

TOWARDS THE DEVELOPMENT OF COLD ATOM-ION QUANTUM NETWORKS

Arijit Sharma

IIT Tirupati, Tirupati, India [email protected]

The development of quantum networks based on interlinked quantum nodes and secure quantum communication channels are a major challenge in the field of quantum information science, including quantum communication, computing, and metrology [1]. Some of the key issues plaguing the practical realization of quantum computers and the development of a robust quantum information network is scalability, long distance entanglement, minimizing decoherence, reducing bit error rate, low cost and operation at ambient (non-cryogenic) temperatures. Till date, the most versatile technologies that have made a critical impact in the development of quantum information processing nodes, are either solid state-based devices such as SQUIDS (super-conducting quantum interference devices), or atomic platforms based on trapped cooled atoms and ions.

Although the quantum nodes of such identical quantum networks communicate (quantum state transfer) with each other via single photons, there is still a major debate over which platform is the best since each has its own merits and demerits. The development of hybrid quantum networks has thus been a new pathway that aims to combine the best of both of both worlds: easy storage and rapid readout of qubits and long storage times for information. Linear ion traps [2] provide significant isolation of quantum particles from the environment and ensure stable operation. On the other hand, magneto-optical traps [3] using Rb (rubidium) atoms form the workhorse of many quantum matter and quantum optics experiments globally.

The fundamental tenet of a quantum network is based on deterministic generation of single photons with a high rate. The main applications for a high-quality single-photon source are quantum key distribution, quantum repeaters and quantum information science. Currently quantum random number generators are in high demand in the market due to potential applications in data security, secure key generation for financial transactions and defense communication, etc. At IIT Tirupati we are proposing the development of cold atom-ion hybrid quantum network that enables communication between two diverse quantum nodes using single photons communicating across the telecom band. We shall discuss our initial efforts using Calcium (Ca) ions and Rubidium (atoms) as quantum nodes towards the development of a quantum network at the telecom wavelength.

References [1] H. J. Kimble, 2008, Nature, 453, 1023–1030. [2] W. Paul, 1990, Rev. Mod. Phys., 62, 531. [3] C. Monroe et al., 1990, Phys. Rev. Lett., 65, 13.

Abstract Number: D5/4-35

ZEPTO SECONDS AND NOT DIPOLE – NEW PHOTOIONIZATION EXPERIMENTS ON STEVES HOME TURF

Reinhard Dorner

Goethe University Frankfurt, Germany [email protected]

How fast is photoionization and how good is dipole approximation – much of our knowledge today on these fundamental questions we owe to Steve. He inspired many experimentalists to venture into these topics. The talk will celebrate his contributions by showing some new gems found experimentally down the roads he paved.

Abstract Number: D5/5-36

AN ULTRAFAST STOPWATCH TO CLOCK MOLECULAR DYNAMICS

Jian Wu

East China Normal University, China [email protected]

We clock the ultrafast dynamics of molecules, ranging from the photoelectron releasing to the bond stretching, by using a polarization-skewed laser pulse, which maps the starting and stopping instants to the emission directions of the photoelectrons and nuclear fragments.

Abstract Number: D5/6-37

EXCITED STATES IN THE LIGHT OF ATOMIC SINGLE- AND MULTI-PHOTON IONIZATION Michael Meyer

European XFEL, Schenefeld, Germany [email protected]

Photoionization of excited atoms has always been of great interest for theorists as well as for experimentalists due to expected strong electron correlations and challenging experimental conditions compared to studies on ground-state atoms. New exciting phenomena were predicted such as the dominance of two-electron processes in single-photon ionization of excited Li atoms [1]. Experiments performed at synchrotron radiation facilities confirmed these predictions and were able to extend the investigations even further towards studies of the dichroism in the photoionization of laser-aligned atoms [2]. With the advent of free- electron lasers sources, which are characterized by the extremely high number of photons available within one ultra-short light pulse, studies of multi-photon processes have entered the focus of atomic research and sequential ionization was found to be the dominating process.Excited states are produced in each individual ionization step influencing strongly the overall yield of the highly charged ions. In some cases, these excited states can directly be addressed by multi-photon ionization [3] revealing again subtle details of photoionization dynamics observed via dichroic phenomena. In addition, non-dipole phenomena, which are well studied in the single photon regime [4], manifest themselves also in sequential photoionization [5].

[1] Z. Felfli and S. Manson, PRL 68, 1687 (1992) [2] M. Meyer, A.N. Grum-Grzhimailo, D. Cubaynes, Z. Felfli, E. Heinecke, S.T. Manson, and P. Zimmermann, PRL 107, 213001 (2011) [3] M. Ilchen, N. Douguet, T. Mazza, A. J. Rafipoor, C. Callegari, P. Finetti, O. Plekan, K. C. Prince, A. Demidovich, C. Grazioli, L. Avaldi, P. Bolognesi, M. Coreno, M. Di Fraia, M. Devetta, Y. Ovcharenko, S. Düsterer, K. Ueda, K. Bartschat, A. N. Grum-Grzhimailo, A. V. Bozhevolnov, A. K. Kazansky, N. M. Kabachnik, and M. Meyer, PRL, 118, 013002 (2017) [4] R. Guillemin, O. Hemmers, D.W. Lindle and S.T. Manson, Radiat. Phys. Chem. 75, 2258 (2006). [5] M. Ilchen, G. Hartmann, E. V. Gryzlova, A. Achner, E. Allaria, A. Beckmann, M. Braune, J. Buck, C. Callegari, R. N. Coffee, R. Cucini, M. Danailov, A. DeFanis, A. Demidovich, E. Ferrari, P. Finetti, L. Glaser, A. Knie, A. O. Lindahl, O. Plekan, N. Mahne, T. Mazza, L. Raimondi, E. Roussel, F. Scholz, J. Seltmann, I. Shevchuk, C. Svetina, P. Walter, M. Zangrando, J. Viefhaus, A. N. Grum-Grzhimailo and M. Meyer, Nat. Comm. 9, 4659 (2018)