Laser-induced nonsequential double ionization: kinematic constraints for the recollision-excitation-tunneling mechanism

TL;DR

This paper analyzes the dynamics of two electrons during laser-induced nonsequential double ionization, identifying momentum constraints and energy limits for the recollision-excitation-tunneling process using quantum orbit methods.

Contribution

It provides a detailed quantum orbit analysis of electron dynamics and momentum constraints in nonsequential double ionization, with new insights into energy cutoffs and electron distributions.

Findings

First electron's kinetic energy cutoff is slightly below 10U_p.

Second electron's maximum energy is 2U_p.

Computed electron-momentum distributions match theoretical estimates.

Abstract

We investigate the physical processes in which an electron, upon return to its parent ion, promotes a second electron to an excited state, from which it subsequently tunnels. Employing the strong-field approximation and saddle-point methods, we perform a detailed analysis of the dynamics of the two electrons, in terms of quantum orbits, and delimit constraints for their momentum components parallel to the laser-field polarization. The kinetic energy of the first electron, upon return, exhibits a cutoff slightly lower than $10U_p$, where $U_p$ is the ponderomotive energy, as in rescattered above-threshold ionization (ATI). The second electron leaves the excited state in a direct ATI-like process, with the maximal energy of $2U_p$. We also compute electron-momentum distributions, whose maxima agree with our estimates and with other methods.