Phase-Dependence of Resonant and Antiresonant Two-Photon Excitations
Abstract
Measurements of the phase of two-photon matrix elements are presented for resonant and antiresonant two-color ionization of helium. A tunable, narrow-bandwidth, near-infrared (NIR) laser source is used for extreme ultra-violet (XUV) high-harmonic generation (HHG). The 15th harmonic of the laser is used within (1+1') XUV+NIR two-photon ionization, and tuned in and out of resonance with members of the 1sp P () Rydberg series, covering a broad spectral range with high spectral resolution. The technique allows to observe characteristic rapid changes in the phase of the two-photon matrix elements around the resonances and, previously unobserved, at the antiresonances between the resonances. Similar effects are observed for (1+2') XUV+NIR three-photon ionization. The experimental results are compared to a perturbative model and to numerical solutions of the time-dependent Schr\"odinger equation (TDSE) in the single active electron (SAE) approximation, elucidating the origin and dependences of the observed phenomena.
Keywords
Cite
@article{arxiv.2105.01598,
title = {Phase-Dependence of Resonant and Antiresonant Two-Photon Excitations},
author = {Lorenz Drescher and Tobias Witting and Oleg Kornilov and Marc J. J. Vrakking},
journal= {arXiv preprint arXiv:2105.01598},
year = {2022}
}
Comments
Accepted version, to be published in Physical Review A. 8 pages, 3 figures