Angular momentum dependence in multiphoton ionization and attosecond time delays
Abstract
Attosecond ionization time-delays at photoelectron energies above typically 10 eV are usually interpreted using the so called asymptotic approximation as a sum of the atomic or molecular delays with a universal laser-induced contribution. Here, we employ a two-harmonic RABITT (Reconstruction of Attosecond Beating by Interference of Two-photon Transitions) configuration to isolate the multiphoton pathways and measure the ionization time delays as a function of the dressing field intensity. We show that the validity of the asymptotic theory can be extended to the threshold or to higher-order contributions by rigorously treating the angular-momentum dependence of the continuum-continuum transitions into universal and easily computable partial-wave-specific correction factors. Our asymptotic treatment is also valid for higher-order interfering amplitudes while significantly simplifying their evaluation and providing a transparent physical interpretation. The validity of the method for atomic and molecular targets in the vicinity of resonances, ionization thresholds, and for both the emission-integrated and angularly resolved signal is confirmed by comparison to ab initio calculations over a wide energy range.
Cite
@article{arxiv.2407.14160,
title = {Angular momentum dependence in multiphoton ionization and attosecond time delays},
author = {Jakub Benda and Zdeněk Mašín and Sreelakshmi Palakkal and Franck Lépine and Saikat Nandi and Vincent Loriot},
journal= {arXiv preprint arXiv:2407.14160},
year = {2024}
}