Photoionization of Xe 5s: angular distribution and Wigner time delay in the vicinity of the second Cooper minimum

Abstract

The angular distribution and photoionization Wigner time delay of Xe 5s photoelectrons are studied in the region of the second Cooper minimum (SCM) using (i) the relativistic multiconfiguration Tamm–Dancoff approximation, (ii) the relativistic-random-phase approximation (RRPA) and (iii) the RRPA-with-relaxation to demonstrate how differing treatments of correlation, and the relativistic interactions, affect the results. The results of the three methods are compared with each other and with available experimental data. The comparison reveals the importance of electron correlations for which a multiconfiguration description of the initial state is essential. The spin-resolved and spin-averaged photoionization time delay results show important signatures in the region of the SCM in the Xe 5s photoionization cross-section.

Photoionization dynamics of Ar trapped in a fullerene anion: Coulomb confinement resonances in 2s subshell and its impact on the 3s subshell

“…The nonrelativistic value of β for a 'ns' subshell is 2 for the case of a closed-shell system. The presence of relativistic interactions, correlations, and confinement can induce deviations from this value 2 [39,[62][63][64]. It is interesting to see whether charged nature of fullerene can induce any deviations from 2.…”

“…These sophisticated experimental techniques enabled physicists to measure the time delay associated with photoionization. A large number of theoretical and experimental works have been done to study the attosecond chronography of free atoms [35][36][37][38][39][40][41][42][43][44][45]. Many theoretical works were performed for the time-delay associated with the atom confined inside fullerene [12,26,27,[46][47][48][49][50][51].…”

Impact of Charge Migration and the Angle-Resolved Photoionization Time Delays of the Free and Confined Atom X@C60

“…depends on sin 2 θ. Thus, for θ = 0 0 , the spin-down contribution vanishes, and the spin average, angle-dependent time delays are exactly the same as the spin-up time delays, while at θ = 90 0 , the spin-up contribution vanishes, and the spin-averaged angle-dependent time delays must follow the spin-down time delays [48].…”

“…According to Equation (12), the spin average time delays are weighted by the absolute squares of the respective depends on 2 sin  . Thus, for θ = 0 0 , the spin-down contribution vanishes, and the spin average, angle-dependent time delays are exactly the same as the spin-up time delays, while at θ = 90 0 , the spin-up contribution vanishes, and the spin-averaged angle-dependent time delays must follow the spin-down time delays [48]. Cooper minima features are not distinguishable in the time delay for the depth 2.2 a.u.…”

Modifications in the angular photoemission time delay in Ar@C60q=−1 : Coulomb confinement resonance as an amplifier of the spin-orbit-interaction-activated interchannel coupling effect

“…In photoionization, the time delay follows the same definition of being the energy derivative of the phase, where the phase associated with the complex ionization matrix element is considered. The time delay is an essential measurable parameter along with cross section, angular distribution asymmetric parameter, etc., which provides information about various correlations and dynamics [10,[18][19][20][21][22][23][24][25][26]. Furthermore, the time-delay measurements give direct knowledge of the phase of the matrix elements, which is otherwise inaccessible.…”