Spatio-temporal interference of photo electron wave packets and time scale of non-adiabatic transition in high-frequency regime

TL;DR

This paper uses the envelope Hamiltonian method to analyze interference effects and optimal pulse durations in high-frequency photoelectron detachment, revealing universal interference mechanisms and a maximum yield condition.

Contribution

It extends previous work by identifying spatial and temporal interference mechanisms in high-frequency ionization and determining the pulse duration that maximizes non-adiabatic transition yield.

Findings

Both spatial and temporal interference mechanisms are universal in high-frequency ionization.

Maximum non-adiabatic transition yield occurs when pulse duration matches electron time-scale.

Envelope Hamiltonian accurately reproduces Schrödinger equation results.

Abstract

The method of the envelope Hamiltonian [K. Toyota, U. Saalmann, and J. M. Rost, New J. Phys. {\bf 17}, 073005~(2015)] is applied to further study a detachment dynamics of a model negative ion in one-dimension in high-frequency regime. This method is based on the Floquet approach, but the time-dependency of an envelope function is explicitly kept for arbitrary pulse durations. Therefore, it is capable of describing not only a photo absorption/emission but also a non-adiabatic transition which is induced by the time-varying envelope of the pulse. It was shown that the envelope Hamiltonian accurately retrieves the results obtained by the time-dependent Schr\"odinger equation, and underlying physics were well understood by the adiabatic approximation based on the envelope Hamiltonian. In this paper, we further explore two more aspects of the detachment dynamics, which were not done in our previous work. First, we find out features of both a {\it spatial} and {\it temporal} interference of photo electron wave packets in a photo absorption process. We conclude that both the interference mechanisms are universal in ionization dynamics in high-frequency regime. To our knowledge, it is first time that both the interference mechanisms in high-frequency regime are extracted from the first principle. Second, we extract a pulse duration which maximize a yield of the non-adiabatic transition as a function of a pulse duration. It is shown that it becomes maximum when the pulse duration is comparable to a time-scale of an electron.