Ionisation of hydrogen molecule in intense ultrashort laser pulses: parallel versus perpendicular orientation

TL;DR

This paper theoretically compares how molecular hydrogen ionizes and gets electronically excited when oriented parallel or perpendicular to intense ultrashort laser pulses, revealing orientation-dependent effects across various laser parameters.

Contribution

It provides a comprehensive, non-perturbative quantum mechanical analysis of hydrogen molecule ionization considering different orientations, pulse lengths, intensities, and photon regimes.

Findings

Orientation significantly affects ionization and excitation probabilities.

Different internuclear distances influence the ionization dynamics.

The study introduces a new atomic model for comparison.

Abstract

A theoretical comparison of the electronic excitation and ionisation behaviour of molecular hydrogen oriented either parallel or perpendicular to a linear polarised laser pulse is performed. The investigation is based on a non-perturbative treatment that solves the full time-dependent Schr\"odinger equation of both correlated electrons within the fixed-nuclei approximation and the dipole. Results are shown for two different laser pulse lengths and intensities as well as for a large variety of photon frequencies starting in the 1- and reaching into the 6-photon regime. In order to investigate the influence of the intrinsic diatomic two-center problem even further, two values of the internuclear separation and a newly developed atomic model are considered.