Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 68, Number 7
Monday–Friday, June 5–9, 2023; Spokane, Washington
Session X11: V: Ultrafast Photoionization and ImagingVirtual Only

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Chair: Carlos Trallero, University of Connecticut Room: Virtual Platform 
Friday, June 9, 2023 8:00AM  8:12AM 
X11.00001: Relativistic and Quadrupole Effects in Photoionization Time Delay in Atoms Rezvan Hosseini, Steven T Manson, Pranawa C Deshmukh EisenbergWignerSmith (EWS) time delay [1] in atomic photoionization is sensitive to the dynamics of atomic electrons on the attosecond time scale, the natural time scale of atomic electron motion [2]. Time delay generally has an angular dependence and calculations have been performed including only dipole transitions [3,4]. In the nonrelativistic dipole approximation, the time delay for atomic nsstates does not depend upon angle; inclusion of relativistic effects of spinflip transitions and nondipole (quadrupole) effects renders the timedelay angledependent. Since the amplitude for the dominant dipole photoionization channel (without spinflip) vanishes at certain angles as a result of angular momentum geometry, quadrupole and spinflip transitions dominate; specifically, where the dipole amplitude vanishes, the time delay is a combination of spinflip dipole and quadrupole photoionization time delay, and the attosecond dynamics of these channels can be investigated. Relativistic expressions have been derived showing where quadrupole and/or spinflip channels determine the time delay. Relativistic random phase approximation (RRPA) [5] calculations for the angular dependance of time delay of nssubshells of noble gas atoms for the angular distribution of time delay including both dipole and quadrupole channels have been studied and the phenomenology is demonstrated. [1] E. P. Wigner, Phys. Rev. 98, 145 (1955); [2] R. Pazourek, S. Nagele and J. Burgdörfer, Rev. Mod. Phys. 87, 765 (2015); [3] J. Wätzel, et al, J. Phys. B 48, 025602 (2015); [4] A. Mandal, et al, Phys. Rev. A 96, 053407 (2017); [5] W. R. Johnson and C. D. Lin, Phys. Rev. A 20, 964 (1979). 
Friday, June 9, 2023 8:12AM  8:24AM 
X11.00002: ASTRA: a scalable wavefunction approach to the photoionization of polyatomic molecules Carlos A Marante Valdes, Felipe Faria, Juan M Randazzo, Barry I Schneider, Jeppe Olsen, Luca Argenti Ultrafast laser technologies keep extending the intensity and frequency of attosecond pulses [1,2]. In molecules, these pulses excite coherent ionization wavepackets that require a correlated wavefunction approach to accurately describe their evolution. We present several ionization observables for diatomic (nitrogen and carbon monoxide) and polyatomic (formaldehyde and ethylene) molecules, computed with the ASTRA suite of codes [3]. ASTRA implements a new approach to the closecoupling representation of the molecular electronic continuum based on highorder transition density matrices (TDM) between correlated ionic states with arbitrary multiplicity, obtained with an extension of LUCIA, a general largescale configurationinteraction code [4], and on hybrid GaussianBspline integrals [5], where the latter can be extended to reach quantization boxes of hundreds atomic units. Total and partial photoionization cross sections together with photoelectron angular distributions compare well with established benchmarks [6,7]. The efficient spinstring formalism of TDM's algorithms in LUCIA [8] makes ASTRA scale favorably with molecular size, thus opening the way to study correlated dynamics in complex molecules. This work is supported by the DOE CAREER grant No. DESC0020311. Part of the calculations used NERSC resources under the contract No. DEAC0205CH11231 and the award BESERCAP0024720. 
Friday, June 9, 2023 8:24AM  8:36AM 
X11.00003: ITVOLT: An Iterative Solver for the TimeDependent Schrödinger Equation Ryan Schneider, Barry I Schneider, Heman Gharibnejad Solutions to the timedependent Schrödinger equation (TDSE) are important for understanding a variety of phenomena in atomic and molecular physics, yet many common numerical approaches struggle to achieve both accuracy and efficiency on the problem. Motivated by this gap, we have developed a new approach that solves the TDSE via an equivalent Volterra integral equation. By applying a Lagrange interpolation of the integrand, our approach converts the Volterra integral equation to a linear system, which is then solved iteratively. The resulting method, which we call ITerative VOLTerra propagator (ITVOLT), is relatively simple to implement, but capable of solving the TDSE over large step sizes and with high accuracy. In this talk, we derive the method, explore its numerical details, and demonstrate with a few examples that it is capable of outperforming more standard approaches such as the shortiterative Lanczos and fourthorder RungeKutta (RK4). While more complex problems require further exploration, we suggest that ITVOLT be considered as a new, front line computational tool for researchers in atomic, molecular, and optical physics. 
Friday, June 9, 2023 8:36AM  8:48AM Withdrawn 
X11.00004: Enhanced ultrafast Xray diffraction by transient resonances Stephan Kuschel, Phay J Ho, Felix Zimmermann, Leonie Flueckiger, Matthew R Ware, Joseph Duris, James P MacArthur, Alberto Lutman, MingFu Lin, Xiang Li, Kazutaka Nakahara, Jeff W Aldrich, Peter Walter, Linda Young, Linda Young, Christoph Bostedt, Agostino Marinelli, Tais Gorkhover Ionization and the resulting sample bleaching is regarded as detrimental for Xray imaging. The Xray scattering signal generally decreases as electrons are removed from the parent ion, a process which ultimately limits the quality of Xray images. However, in this study we find that ionization can create shortlived electronic states which are beneficial for imaging and increase the scattering cross section compared to the neutral atom. We compared snapshots from individual 100 nm Xe nanoparticles as a function of the Xray pulse duration and incoming Xray intensity in the vicinity of the Xe Mshell resonance. Surprisingly, images recorded with few femtosecond and subfemtosecond pulses are up to 10 times brighter than the static linear model predicts. Our MonteCarlo simulation and statistical analysis of the entire data set confirms these findings and attributes the effect to transient resonances. Our simulations suggest that the scattering cross section may increase by several orders of magnitude when targeting specific resonances. Our study guides the way towards CDI with unprecedented combination of spatial and temporal resolution at the nanoscale. 
Friday, June 9, 2023 8:48AM  9:00AM 
X11.00005: Ultrafast 3D XRay Fluorescence Imaging Robert G Radloff, Miklós Tegze, Stephan Kuschel, Anatoli Ulmer, Lara Rönnebeck, Siqi Li, Andrew L Aquila, Faigle Gyula, Carina Hedrich, Dimitrios Kazasis, Mengning Liang, Takahiro Sato, Peihao Sun, Yanwen Sun, Yasin Ekinci, Diling Zhu, Robert Zierold, Felix Zimmermann, Jerome B Hastings, Christoph Bostedt, Ichiro Inoue, Taito Osaka, Agostino Marinelli, Tais Gorkhover Coherent diffraction imaging with Xray freeelectron lasers (FELs) combines high spatial and temporal resolutions, but is limited to forward scattering and thus, 2D projections of the sample. Here, we study the potential of incoherent diffractive imaging (IDI) proposed by Classen et al. (2017) which is based on fluorescence emission from the specimen into the full solid angle. 
Friday, June 9, 2023 9:00AM  9:12AM 
X11.00006: Relativistic and correlation effects in np photoionization Cooper minimum of highZ atoms Saumyashree Baral, Jobin Jose, Pranawa C Deshmukh, Steven T Manson When the initial bound state radial function involved in the photoionizing transition has a node, the photoionization often passes through a zero, or nearzero, that leaves imprints on photoionization parameters like cross section, angular distribution asymmetry parameter, phase shift and time delay. This minimum is wellknown as the Cooper minimum (CM) [1,2] which is quite sensitive to relativistic and correlation effects. Earlier, the CM for the 6p subshell were studied for highZ atoms up to Z=100 using uncorrelated nonrelativistic DiracSlater centralfield wave functions [3,4]. The present work extends these studies up to Z=120, using the correlated relativistic random phase approximation (RRPA) [5] and the DiracFock independent particle approximation [6] for comparison; photoionization also from the 5p and 4p shells has also been examined. In particular, the atoms Rn (Z=86), Ra (Z=88), No (Z=102), Cn(Z=112), Og (Z=118), Ubn (Z=120) are investigated. Spinorbit and interchannel coupling effects are of crucial importance to location of the CM at high Z. [1] J. W. Cooper, Phys. Rev. A, 128, 681 (1962). [2] W. R. Johnson and K. T. Cheng, Phys. Rev. A 20, 978 (1979). [3] S. T. Manson, et al, Phys. Rev. A 28 (1983). [4] P. C. Deshmukh, B. R. Tambe and S. T. Manson, Austral. J. Phys. 39, 679 (1986). [6] M. Reiher and A. Wolf, Relativistic Quantum Chemistry: The Fundamental Theory of Molecular Science, 2nd Edition (WileyVCH, Wertheim, Germany, 2015). [5] W.R. Johnson and C.D. Lin, Phys. Rev. A 20, 964 (1979). 
Friday, June 9, 2023 9:12AM  9:24AM 
X11.00007: The impact of nonessential states in nearresonant twophoton ionization of hydrogen Andras Csehi, Xu Zhang, Yueming Zhou, Yijie Liao, Yongkun Chen, Jintai Liang, Qinghua Ke, Min Li, Peixiang Lu By numerically solving the threedimensional timedependent Schrodinger equation, twophoton ionization of hydrogen is investigated at the nearresonant frequencies of the 1s2p transition. Due to the Rabi oscillations between the 1s and 2p states, the photoelectron energy spectrum exhibits the AutlerTownes (AT) doublet and we focus on its spectral characteristics. Developing a minimal threelevel model that is fully supported by the accurate 3D TDSE simulations, we demonstrate the role of the ac Stark shifts and the nonresonant ionization pathway in the energy splitting, asymmetry and angular distribution of the lower and higher energy peaks of the AT doublet. Furthermore, we show how these spectral features can be controlled with the actual choice of the laser parameters (Phys. Rev. A 106, 063114, 2022). 
Friday, June 9, 2023 9:24AM  9:36AM 
X11.00008: Trojan Wave Packets in the Circularly Polarized and the Magnetic Fields on the multilayer Langmuir type $(1)$ Helium trajectories with the interlayer polygon type change Matt Kalinski Some time ago we have discovered the theorem stating that the number of a distinct classically rotating frozen electron configurations in the external magnetic field, the nuclear ion field and the corotating electric field may be at least the product of all foldings of total force surfaces (the maximal number any straight line may cut the surface which notrivially is 2) obtained by putting each of the multidimensional gradient component of the Zero Velocity Surface to zero. Consistently with it we have discovered a several highly symmetric configurations originated from the Langmuir type $(1)$ ``Hoop Earrings" rotating Heliumlike model trajectories [1] with further small discrete rotational symmetry distortion by the Circularly Polarized electromagnetic field without the loss of its nature. Those were the multielectron atom trajectories consisting of two or many layers of electrons moving in phase on circles with electron configurations placed at the vertexes of angles of identical by type but only scaled regular polygons parallel in space which additionally could be also symmetrically twisted between each other. Here we extend the case to the situation when the neighboring layer polygons are planesymmetrically of a different kind. For example the hexagon in the central plane may accompany two triangles placed symmetrically one in the upper paraller plane and the other in the lower or the octagon may similarly neighbor two squares etc. The classical stabilization of the trajectories by the combination of fields further leads to the existence of nondispersing localized Trojanlike wave packets moving around the trajectories. The time dependent Hartree simulations of such Wave Packets as well as those with the Time Dependent Quantum Diffusion Monte Carlo Method are conducted. [1] M. Kalinski, et al., Phys. Rev. Lett. {bf 95}, 103001, (2005). 
Friday, June 9, 2023 9:36AM  9:48AM 
X11.00009: Timeresolved photoinduced dynamics of cis,cis1,3cyclooctadiene (COD) studied by Ultrafast Electron Diffraction Sri Bhavya Muvva, Yusong Liu, Pratip Chakraborty, Pedro Nunes, Spiridoula Matsika, Thomas Weinacht, Martin Centurion We investigated realtime photoinduced structural dynamics of a largeflexible cyclic conjugated diene molecule cis,cis1,3cyclooctadiene (COD), with an aim to extend the current knowledge beyond small rigid systems, such as 1,3cyclohexadiene (CHD). We excited COD in the gasphase with a 200 nm laser and performed measurements with the ultrafast electron diffraction setup in the SLAC MeVUED facility. We followed the photoinduced structural dynamics and determined photo products by a fittingbased analysis with the aid of trajectory surface hopping calculations. We found hot groundstate of COD and the electrocyclic ring closure product bicyclo[4.2.0]oct7ene (BCO) to be the main products. Our results indicate that most of the population reaches the ground state within a time of 200 fs and that the BCO is formed soon after the wavepacket reaches the ground state. Through comparison of the measured and calculated observables, we identified a periodic breathing motion from the hot groundstate of COD. The combination of a structurally sensitive experiment and highlevel theory highlights the photochemistry and unique structural dynamics in the larger cyclic conjugated molecular system. 
Friday, June 9, 2023 9:48AM  10:00AM 
X11.00010: Revealing multitime quantum statistics without measurement backaction Chunyang Luan, Pengfei Wang, Hyukjoon Kwon, Wentao Chen, Kim M. S., Mu Qiao, Kihwan Kim, Zinan Zhou, Kaizhao Wang, Chunyang Luan Due to the principle of quantum mechanics that measurement disturbs a quantum state, it is a major challenge in obtaining quantum statistics, such as quantum correlation function and quasiprobability distribution. We propose an ancillaassisted measurement scheme to detour the measurementinduced backaction, which can be applied for any multitime measurements. With performing sequential positive operatorvalued measurements at each timepoint, the quantum statistics are reconstructed by weighting their outcomes differently. We employ ^{171}Yb^{138}Ba ions as the systemancilla system to demonstrate the multitime measurements without disturbing the system state, and the two and threetime quantum correlation functions and quasiprobability distributions are reconstructed from the ancilla measurement outcomes. The marginal distribution is verified to be unaffected by the measurement at each timepoint, and the nonclassical feature of the reconstructed distribution is identified by the negativity in the joint quasiprobability distribution and the violation of the LeggettGarg inequality. 
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