Bulletin of the American Physical Society
53rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 67, Number 7
Monday–Friday, May 30–June 3 2022; Orlando, Florida
Session M04: Photoionization, Photodetachment, and PhotodissociationRecordings Available
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Chair: Börge Hemmerling, UC Riverside Room: Salon 3/4 |
Wednesday, June 1, 2022 2:00PM - 2:12PM |
M04.00001: Photoionization of the Mg-like S4+ Ion in Ground and Metastable States: Experiment and Theory Thomas W Gorczyca, M. Fatih Hasoglu, Jean-Paul Mosnier, Eugene T Kennedy, Denis Cubayne, Jean-Marc Bizau, Segolene Guilbaud, Christophe Blancard We report calculations and measurements of the absolute photoionization cross section of the magnesium-like S4+ ion over the 160-270 eV photon energy range. The experiments were performed with the merged photon-ion MAIA apparatus at the Soleil synchrotron radiation facility. Single and double ionization ion yields produced by the photoionization of the 2p subshell of the S4+ ion both from the 2p63s2 1S0 ground state and the 2p53s3p(3P0,2) metastable levels were observed, as well as 2s excitations. Calculations of the photoionization cross sections were carried out using Multi-Configuration Dirac-Fock and R-matrix codes and the results are compared with the experimental data. |
Wednesday, June 1, 2022 2:12PM - 2:24PM |
M04.00002: Hole localization in the Cl (2p)-1 ionization of CCl4 Robert R Lucchese, Cynthia S Trevisan, Carlos Marante, Thomas N Rescigno, William McCurdy The Cl (2p)-1 photoionization of CCl4 can produce four 2P1/2 and four2P3/2 states of CCl4+. Each set of four states is nearly degenerate so that to describe a dissociative ionization experiment one can use either a coherent superposition of the states that are either localized or delocalized across the four Cl atoms. Depending on the dynamics of the dissociation process, an experiment which measures the photoelectron in coincidence with the fragments would measure the molecular frame photoelectron angular distributions (MFPADs) that are characteristic of either localized or delocalized hole states. We have computed the MFPADs for these two cases to understand the extent to which an experiment could determine the degree of hole localization. We use the decoupling of the hole states on the different Cl atoms to simplify the calculation to a three channel calculation including only the three Cl (2p)-1 hole states on one atom. Additionally we use both the grid and basis-set complex Kohn methods to assess the adequacy of the basis sets used. Finally, we use a three channel basis-set complex Kohn calculation to predict the MFPADs that can be measured from localized and delocalized representations of this core ionization process. |
Wednesday, June 1, 2022 2:24PM - 2:36PM |
M04.00003: Photoionization Branching Ratios of Spin-Orbit Doublets in Rn Far Above Thresholds C. Rasadi Munasinghe, Steven T Manson, Pranawa C Deshmukh At energies far above the branching ratios of the photoionization cross section of spin-orbit (nl) doublets must go to its statistical value of (l+1)/l in the absence of relativistic effects. Thus, alteration of the branching ratio from its statistical value at higher energies indicates relativistic interactions on the initial and final state radial wave functions as predicted earlier [1] and verified experimentally recently [2]. Here we report on a study of Rn (Z=86) using the relativistic-random-phase approximation (RRPA) based on the Dirac equation, which includes relativistic interactions in an ab initio manner and many-body correlations. The results show that branching ratios well above the threshold are not only energy-dependent and move further away from the nonrelativistic value with increasing energy, but also that interchannel coupling effects in the vicinity of inner-shell thresholds, as suggested by earlier studies [3,4]. Particularly strong interchannel effects are seen near the 3d thresholds. . [1] A. Ron, Y. S. Kim, R. H. Pratt, Phys. Rev. A 24, 1260 (1981); [2] R. Puettner, et al, J. Phys. B 54, 085001 (2021). [3] E. W. B. Dias, et al, Phys. Rev. Lett. 78, 4553 (1997); [4] W. Drube, et al, J. Phys. B 46, 245006 (2013). |
Wednesday, June 1, 2022 2:36PM - 2:48PM |
M04.00004: Correlation effects in molecular ionization with ASTRA, a transition-density-matrix approach to close coupling Carlos A Marante Valdes, Juan M Randazzo, Heman Gharibnejad, Barry I Schneider, Jeppe Olsen, Luca Argenti XUV and soft-x-ray ultrafast technologies continue extending attosecond-pulse to shorter durations, larger intensities and larger energies [1,2]. The correlated and entangled character of the ionization states obtained with such pulses requires a wave-function approach to describe coherent superpositions of multiple photoelectron-photoion pairs. We present ionization observables for the nitrogen and formaldehyde molecules computed with the ASTRA code (AttoSecond TRAnsitions). ASTRA implements a new approach to the close-coupling representation of the electronic continuum based on high-order transition density matrices between correlated ionic states, obtained with an extension of LUCIA [3], and on hybrid Gaussian-B-spline integrals [4]. Thanks to this approach, ASTRA scale favorably with the molecular size. Resonant photoionization cross sections and photoelectron angular distributions compare well with theoretical and experimental results in the literature (e.g. [5,6]), paving the way to the applications of ASTRA to more complex molecules. |
Wednesday, June 1, 2022 2:48PM - 3:00PM |
M04.00005: Study of level-specific photoionization and electron-ion recombination of Ca~XVIII - Ca~~XX using unified method Sultana N Nahar Study of characteristic features of the inverse process of electron-ion |
Wednesday, June 1, 2022 3:00PM - 3:12PM |
M04.00006: A kinematically complete measurement of the direct photo double ionization of ethylene molecules Moniruzzaman Shaikh, Wael Iskandar, Sun Y Lee, Daniel S Slaughter, Thorsten Weber The absorption of a single extreme ultraviolet photon by an atom or molecule leads to the emission of two correlated electrons in the direct Photo Double Ionization (PDI) process. We investigated the PDI of single ethylene molecules near its threshold (40 eV) in order to unravel fundamental intertwining of electron correlation in inter-shell and intra-shell cases and the subsequent molecular dynamics. We particularly focused on the reaction producing a symmetric breakup of the molecule. |
Wednesday, June 1, 2022 3:12PM - 3:24PM |
M04.00007: Single Photoionization of Cl2+ induced by synchrotron radiation. Guillermo Hinojosa, Sultana N Nahar, David A Kilcoyne, Edgar M Hernández, Antonio M Juárez, Lorenzo Hernández, Armando Antillón, Alejandro Morales-Mori, Olmo González, Aaron M Covington, Vern Davis, Dag Hanstorp, Dominic Calabrase The single photoionization of Cl III induced by radiation is being studied both, theoretically and experimentally, in the radiation energy range from below ionization threshold up to 20 eV above it. For the theory, ab-initio R-matrix method is being implemented. For the experiment, high resolution synchrotron radiation from the Advanced Light Source at the LBNL was merged with an ion-beam of Cl2+ to generate Cl3+ ions which intensity was monitored alongside with other relevant parameters. Several resonant features lying above a non-resonant background below and above threshold have been observed and, will be discussed with the help of the R-matrix theory. |
Wednesday, June 1, 2022 3:24PM - 3:36PM |
M04.00008: Single ionization of He by energetic protons in a parabolic quasi-Sturmians approach Lorenzo Ugo Ancarani, Sergey A Zaytsev, Alexander S Zaytsev, D S Zaytseva, V V Nasyrov, Konstantin A Kouzakov Fully differential cross sections for single ionization of helium induced by 1 MeV proton impact are calculated using a parabolic convoluted quasi-Sturmian (CQS) method. In the framework of this approach the transition amplitude is extracted directly from the asymptotic behavior of the solution of an inhomogeneous Schrödinger equation for the Coulomb three-body system (e-, He+, p+). The driven equation is solved numerically by expanding in convolutions of quasi-Sturmians for the two-body proton-He+ and electron-He+ systems. It is found, at least in the high energy limit, that the calculated cross sections within the proposed CQS method converge pretty fast as the number of terms in the expansions is increased, and are in reasonable agreement with experimental data and other theoretical results. |
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