Origin of Plateau and Species dependence of Laser-Induced High-Energy Photoelectron Spectra

TL;DR

This paper investigates the origin of high-energy plateau electrons in laser-induced photoelectron spectra, revealing they result from backscattering of returning electrons, and introduces a rescattering theory that predicts spectra without solving complex equations.

Contribution

It presents a quantitative rescattering theory explaining species and intensity dependence of high-energy photoelectron spectra, bypassing the need for solving the time-dependent Schrödinger equation.

Findings

Plateau electrons originate from backscattering of returning electrons.

The theory explains flat or steep spectra based on elastic scattering cross sections.

The approach accurately predicts energy and momentum distributions without complex simulations.

Abstract

We analyzed the energy and momentum distributions of laser-induced high-energy photoelectrons of alkali and rare gas atoms. For the plateau electrons with energies above $4U_p$, ($U_p$ is the ponderomotive energy), in the tunneling ionization regime, we showed that they originate from the backscattering of laser-induced returning electrons. Using the differential elastic scattering cross sections between the target ion with \emph{free} electrons, we explain experimental observations of whether the plateau electron spectra is flat or steeply descending, and their dependence on species and laser intensity. This quantitative rescattering theory can be used to obtain energy and momentum distributions of plateau electrons without the need of solving the time-dependent Schr\"{o}dinger equation, but with similar accuracy.