Laser-assisted photoionization of argon atoms: streaking, sideband and pulse train studying cases

TL;DR

This paper provides a theoretical analysis of laser-assisted photoionization of argon atoms, exploring how different laser pulse configurations influence the photoelectron spectra using the strong-field approximation.

Contribution

It introduces a comprehensive theoretical framework for understanding photoelectron spectra in laser-assisted ionization, applicable to various atomic species and laser configurations.

Findings

Distinct PES features are linked to intracycle and symmetry properties.

Generalized energy conservation laws explain PES structures.

The scheme is adaptable to other atoms and field setups.

Abstract

We present a theoretical study of atomic laser-assisted photoionization emission (LAPE). We consider an atom driven by a linearly polarized XUV laser in two different scenarios: i) a single attosecond pulse (in both the streaking and sideband regimes) and ii) an attosecond pulse train. The process takes place assisted by a linearly polarized infrared (IR) laser field. In all these cases the energy and angle-resolved photoelectron spectrum (PES) is determined by a leading contribution, related to the intracycle factor [Gramajo et al., J. Phys. B 51, 055603 (2018)], complemented by other ones, derived from the periodicity and symmetry properties of the dipole transition matrix with respect to the IR field. Each of these terms imprint particular features in the PES that can be straightforwardly understood in terms of generalized energy conservation laws. We investigate in detail these PES structures, in particular, for the case of argon initially in the 3s quantum state. Our theoretical scheme, based on the strong-field approximation (SFA), can be applied, however, to other atomic species and field configurations as well.