Photoelectron Angular Distributions of Nonresonant Two-Photon Atomic Ionization Near Nonlinear Cooper Minima

TL;DR

This paper theoretically investigates how two-photon ionization of neutral atoms affects photoelectron angular distributions, especially near nonlinear Cooper minima, using relativistic perturbation theory and numerical calculations.

Contribution

It reveals that significant variations in angular distributions occur near nonlinear Cooper minima, expanding understanding beyond resonance effects.

Findings

Angular distributions vary strongly near nonlinear Cooper minima.

Theoretical predictions are demonstrated on magnesium atom.

Dependence on light polarization and energy is characterized.

Abstract

Photoelectron angular distributions of the two-photon ionization of neutral atoms are theoretically investigated. Numerical calculations of two-photon ionization cross sections and asymmetry parameters are carried out within the independent-particle approximation and relativistic second-order perturbation theory. The dependence of the asymmetry parameters on the polarization and energy of the incident light as well as on the angular momentum properties of the ionized electron are investigated. While dynamic variations of the angular distributions at photon energies near intermediate level resonances are expected, we demonstrate that equally strong variations occur near the nonlinear Cooper minimum. The described phenomena is demonstrated on the example of two-photon ionization of magnesium atom.