Ionization of Atoms by Intense Laser Pulses

TL;DR

This paper investigates the ionization of a hydrogen atom by intense, short infrared laser pulses, showing that at high pulse intensities the atom is almost certainly ionized with electrons ejected in a specific direction, aligning with experimental observations.

Contribution

It provides a theoretical analysis of ionization probabilities and electron ejection directions in the high-intensity regime, extending understanding of laser-atom interactions.

Findings

Ionization probability approaches 1 as pulse intensity increases.

Electrons are ejected into a narrow cone in the direction of -A.

Results qualitatively agree with experimental data.

Abstract

The process of ionization of a hydrogen atom by a short infrared laser pulse is studied in the regime of very large pulse intensity, in the dipole approximation. Let $A$ denote the integral of the electric field of the pulse over time at the location of the atomic nucleus. It is shown that, in the limit where $|A| \to \infty$, the ionization probability approaches unity and the electron is ejected into a cone opening in the direction of $-A$ and of arbitrarily small opening angle. Asymptotics of various physical quantities in $|A|^{-1}$ is studied carefully. Our results are in qualitative agreement with experimental data reported in \cite{1,2}.