Rescattering effects in laser-assisted electron-atom bremsstrahlung

TL;DR

This paper investigates rescattering effects in laser-assisted electron-atom bremsstrahlung using TDER theory, revealing plateau structures in spectra and providing an analytic quantum description of the process, including in Coulomb fields.

Contribution

It introduces a detailed quantum analysis of LABrS rescattering effects using TDER theory, with an analytic description of spectra and a generalization to Coulomb fields.

Findings

Rescattering plateau structures are observed in high-energy LABrS spectra.

An analytic quantum description of LABrS amplitude is derived for low-frequency fields.

The TDER framework is extended to include Coulomb field effects.

Abstract

Rescattering effects in nonresonant spontaneous laser-assisted electron-atom bremsstrahlung (LABrS) are analyzed within the framework of time-dependent effective-range (TDER) theory. It is shown that high energy LABrS spectra exhibit rescattering plateau structures that are similar to those that are well-known in strong field laser-induced processes as well as those that have been predicted theoretically in laser-assisted collision processes. In the limit of a low-frequency laser field, an analytic description of LABrS is obtained from a rigorous quantum analysis of the exact TDER results for the LABrS amplitude. This amplitude is represented as a sum of factorized terms involving three factors, each having a clear physical meaning. The first two factors are the exact field-free amplitudes for electron-atom bremsstrahlung and for electron-atom scattering, and the third factor describes free electron motion in the laser field along a closed trajectory between the first (scattering) and second (rescattering) collision events. Finally, a generalization of these TDER results to the case of LABrS in a Coulomb field is discussed.