Relativistic calculations of angular dependent photoemission time delay

Angular dependence of photoemission time delay for the valence $np_{3/2}$ and $np_{1/2}$ subshells of Ar, Kr and Xe is studied in the dipole relativistic random phase approximation. Strong angular anisotropy of the time delay is reproduced near respective Cooper minima while the spin-orbit splitting affects the time delay near threshold

Effects of spin-orbit-interaction-activated interchannel coupling on photoemission time delay

Spin-orbit-interaction-activated interchannel coupling (SOIAIC) has been investigated theoretically in the time delay domain for 3d photoemission in the isoelectronic sequence I−, Xe, and Cs+ using the relativisticrandom-phase approximation with relaxation. The results show that SOIAIC becomes more important with increasing nuclear charge, and that time delay is affected more strongly than cross sections or photoelectron angular distribution β parameters.S.B. acknowledges the support of the Director, Indian Institute of Technology Tirupati. The work of S.T.M. was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Grant No. DE-FG02- 03ER15428

Relativistic calculations of angle-dependent photoemission time delay

Angular dependence of photoemission time delay for the valence np 3/2 and np 1/2 subshells of Ar, Kr, and Xe is studied in the dipole relativistic random phase approximation. Strong angular anisotropy of the time delay is reproduced near respective Cooper minima while the spin-orbit splitting affects the time delay near threshold

Interchannel coupling effects in the spin polarization of energetic photoelectrons

Effects of the interchannel coupling on the spin polarization of energetic photoelectrons emitted from atomic Ne valence subshells are examined. Like previously obtained results for cross sections and angular distributions, the photoelectron spin polarization parameters too are found considerably influenced by the coupling. The result completes a series of studies to finally conclude that the independent particle description is inadequate for the {\em entire} range of photoionization dynamics over the {\em full} spectral energy domainComment: 7 pages, 5 figures, accepted in Phys. Rev.

Photoionization of Atomic Systems Using the Random-Phase Approximation Including Relativistic Interactions

Approximation methods are unavoidable in solving a many-electron problem. One of the most successful approximations is the random-phase approximation (RPA). Miron Amusia showed that it can be used successfully to describe atomic photoionization processes of many-electron atomic systems. In this article, the historical reasons behind the term “random-phase approximation” are revisited. A brief introduction to the relativistic RPA (RRPA) developed by Walter Johnson and colleagues is provided and some of its illustrative applications are presented

Photoionization of Atomic Systems Using the Random-Phase Approximation Including Relativistic Interactions

Approximation methods are unavoidable in solving a many-electron problem. One of the most successful approximations is the random-phase approximation (RPA). Miron Amusia showed that it can be used successfully to describe atomic photoionization processes of many-electron atomic systems. In this article, the historical reasons behind the term “random-phase approximation” are revisited. A brief introduction to the relativistic RPA (RRPA) developed by Walter Johnson and colleagues is provided and some of its illustrative applications are presented

Interchannel Coupling in the Photoionization of Atoms and Ions in the X-Ray Range

To understand how this interchannel coupling, so important in neutral atoms, applies to positive ions, a research program has been initiated to deal with this question, i.e., a program to quantify the effects of interchannel coupling in ionic photoionization, thereby assessing existing photoionization data bases in the x-ray region. To accomplish this task, we have employed the Relativistic Random-Phase-Approximation (RRPA) methodology which includes significant aspects of electron-electron correlation, including interchannel coupling. The RRPA methodology has been found to produce excellent agreement with experiment for neutral Ne at photon energies in the 1 keV range

Dominance of correlation and relativistic effects on photodetachment time delay well above threshold

Wigner time delay in photodetachment from the 3p3/2 and 3p1/2 subshells of Cl− has been studied in the vicinity of the 2p3/2 and 2p1/2 thresholds, using the relativistic random phase approximation (RRPA). The results show time delay spectra dominated by many-body correlations along with very complicated dependence on the energy over a broad spectral range. In addition, the time delay spectra of the two spin-orbit split 3p subshells differ significantly from one another, thereby revealing the importance of relativistic effects even in the case of a low-Z system.This work is enabled by the infrastructure and support extended to our research group by the Director, Indian Institute of Technology Tirupati, which includes hospitality to S.S. and S.T.M. This work was supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy, Grant No. DE-FG02-03ER15428

Strong dependence of photoionization time delay on energy and angle in the neighborhood of Fano resonances

© 2019 American Physical Society. We uncover dramatic variations of the Wigner photoemission time delay with energy and angle in the vicinity of a Fano resonance with the time delay taking opposite signs at different angles at the same energy as well as at the opposite sides of the resonance at the same angle. These variations are illustrated by choosing the Ne 2s→3p autoionizing state as a case study. Moreover, we demonstrate the existence of strikingly significant changes in time delay due to relativistic effects despite Ne being a low-Z atom. This finding shows the possibility for utilizing time delay chronoscopy as a route towards experimental probing of relativistic interactions and the phases of individual transition matrix elements upon atomic photoionization of low-Z atoms. Finally, we develop a practical parametrization to model and explain the angle and energy variation of the autoionizing resonance time delay in the nonrelativistic limit