Factorisation of laser pulse ionisation probabilities in the multiphotonic regime

TL;DR

This paper develops a factorization approach for laser-induced ionisation probabilities in the multiphotonic regime, enabling simplified analysis of complex atomic and molecular systems with rapid convergence of the series expansion.

Contribution

It introduces a multipole-like expansion that separates electromagnetic and target structure effects, improving interpretability and computational efficiency.

Findings

Series expansion converges rapidly with few terms needed for accuracy.

Factorization aids in understanding complex atomic and molecular ionisation dynamics.

Method applicable to both atomic hydrogen and molecular ions.

Abstract

We present a detailed study of the ionisation probability of H and H$_{2}^{+}$ induced by a short intense laser pulse. Starting from a Coulomb-Volkov description of the process we derive a multipole-like expansion where each term is factored into two contributions: one that accounts for the effect of the electromagnetic field on the free-electron final-state and a second factor that depends only on the target structure. Such a separation may be valuable to solve complex atomic or molecular systems as well as to interpret the dynamics of the process in simpler terms. We show that the series expansion converges rapidly, and thus the inclusion of the first few terms are sufficient to produce accurate results.