Photoionization Processes

James A. R. Samson

Steven Trent Manson, Zikri Zikri, Altun ALTUN +3 more

Stefano Simonucci, Renato Colle

M. Ya. Amusia

Yidan Xu, Lulu Han, Wenyu Jiang +5 more

Photoionization is one of the most fundamental processes in light-matter interaction. Advanced attosecond photoelectron spectroscopy provides the possibility to characterize the ultrafast photoemission process in an extremely short attosecond time scale. Following scattering symmetry rules, residual ions encode ultrafast photoionization prints at the instant of electron removal forming an alternative electron emission chronoscope. Here, we experimentally illustrate the attosecond ion reconstruction of attosecond beating by interference of two-photon transition (RABBIT)-like interferometry through the development of high-resolution ion momentum detection in atomic photoionization processes. Our ion interferometry presents identical momentum- and time-dependent scattering phase shift, as we observed in photoelectron spectroscopy, and thus demonstrates that ion interferometry can be a possible alternative attosecond approach to resolve the photoionization process, without the electron homogeneity limitation.

M. Marinescu, H. R. Sadeghpour, A. Dalgarno

Two-color two-photon photoionization of hydrogen and alkali atoms is presented. The method based on a perturbation expansion is valid for low to moderately intense radiation fields. Three processes are considered leading to the photoionization. For the first process both photons are below threshold, and for the second process one photon is above the threshold with an energy less than the final energy of the photoelectron. The last process is identical to the continuum Raman (Compton) scattering where the first photon is absorbed high in the continuum and the second low energy photon is scattered. Photoionization cross sections of hydrogen and the alkali atoms are given as functions of the first photon energy and the photoelectron energy.