2016/05/15 by I A Ivanov, И. А. Иванов, Jan Marcus Dahlström +9
Chemistry · Physics and Astronomy · #Advanced Chemical Physics Studies #Laser-Matter Interactions and Applications #Mass Spectrometry Techniques and Applications #physics.atom-ph
paper · pdf · doi:10.48550/arxiv.1605.04539
arxiv created 2016/05/15 · arxiv updated 2016/05/17
We investigate an angular dependence of the photoemission time delay in helium as measured by the RABBITT (Reconstruction of Attosecond Beating By Interference of Two-photon Transitions) technique. The measured time delay τa=τW+τcc contains two distinct components: the Wigner time delay τW and the continuum-continuum CC) correction τcc. In the case of helium with only one 1s→ Ep photoemission channel, the Wigner time delay τW does not depend on the photoelectron detection angle relative to the polarization vector. However, the CC correction τcc shows a noticeable angular dependence. We illustrate these findings by performing two sets of calculations. In the first set, we solve the time-dependent Schrödinger equation for the helium atom ionized by an attosecond pulse train and probed by an IR pulse. In the second approach, we employ the lowest order perturbation theory which describes absorption of the XUV and IR photons. Both calculations produce close results in a fair agreement with experiment.