Angle-dependent time delay in two-color XUV+IR photoemission of He and Ne

Abstract

We solve the time-dependent Schrödinger equation for a noble gas atom (He and Ne) driven by an ionizing XUV and dressing IR fields. From this solution we deduce an angular dependence of the photoemission time delay as measured by the RABBITT (reconstruction of attosecond beating by interference of two-photon transitions) technique. We use a recent angle-resolved RABBITT measurement on helium [S. Heuser et al., Phys. Rev. A 94, 063409 (2016)] to test and calibrate our theoretical model. Based on this calibration, we find no significant difference between the time delay in He measured in the angle-integrated RABBITT experiments [C. Palatchi et al.,

Time delays from one-photon transitions in the continuum

“…Although the observed phase difference has previously not been recognized and analyzed, the above observations are, in fact, noticeable also in earlier numerical simulations [19,21]. Qualitatively the trend mirrors the observation of partial-wave interferences resulting in electronspin polarization in one-photon bc-transitions [43][44][45].…”

“…For such continuumcontinuum transitions, we measure a delay between outgoing s-and d-electrons as large as 12 as close to the ionisation threshold in helium. Both single-active-electron and first-principles ab initio simulations confirm this observation for helium and hydrogen, demonstrating the universality of the observed delays.Recently, experimental evidence of a strong effect of the IR-induced cc-transitions on the angular dependence of the total photoemission delays has been reported [14,15] stimulating several independent investigations on the origin of this effect [21,[23][24][25][26][27]. In this work, arXiv:1907.03607v1 [physics.atom-ph]…”

“…Recently, experimental evidence of a strong effect of the IR-induced cc-transitions on the angular dependence of the total photoemission delays has been reported [14,15] stimulating several independent investigations on the origin of this effect [21,[23][24][25][26][27]. In this work, arXiv:1907.03607v1 [physics.atom-ph]…”

Simulation of angular-resolved RABBITT measurements in noble-gas atoms

“…These experiments bring sensitive information on ultrafast electron dynamics influenced by correlation and exchange effects. Theoretical modeling of the angular resolved RABBITT process have been provided within the framework of lowest order perturbation theory (LOPT) [4,5] and non-perturbatively, by solving the time-dependent Schrödinger equation (TDSE) [2,6]. As in our preceding paper [6], we solved TDSE for a noble gas atom (He and Ne) driven by an ionizing XUV and dressing IR fields in the configuration of a typical RABBITT measurement.…”

“…Solution of the TDSE in [6] was obtained in the single active electron (SAE) approximation and utilized the optimized effective potentials (OEP) of Sarsa et al [9]. While such approach was found to be valid for He, this remains to be shown for Ne and heavier noble gas atoms.…”