Regular Article

Physical mechanisms encoded in photoionization yield from IR+XUV setups^⋆

¹ Department of Physics, University of Ottawa, K1N 6N5 Ottawa, ON, Canada
² Laboratoire de Physique Théorique, Université de Toulouse, CNRS, UPS, Toulouse, France
³ Institute of Applied Physics and Computational Mathematics, 100088 Beijing, P.R. China
⁴ Institut für theoretische Physik, Universität Erlangen, Erlangen, Germany
⁵ School of Mathematics and Physics, Queen’s University, Belfast, UK

^a e-mail: suraud@irsamc.ups-tlse.fr

Received: 21 September 2018
Received in final form: 5 July 2019
Published online: 22 October 2019

Abstract

We theoretically examine how and to which extent physical processes can be retrieved from two-color pump-probe experiments of atomic and molecular gases driven by an attosecond XUV pulse train and an infrared (IR) pulse. The He atom, the N₂ molecule and Na clusters are investigated with time-dependent density functional theory. Results are interpreted on the basis of a simple model system. We consider observables most commonly used in experiments: ionization yield, photo-electron spectra, and angular distributions. We find that the basic time-dependent signatures are dominated by the interplay of IR laser and continuum electrons. System information, contained in the signal, will in general require careful disentangling from the effects of photon-electron dynamics.