Propagation of the photoelectron wave packet in an attosecond streaking experiment

TL;DR

This paper investigates how photoelectron wave packets propagate in an attosecond streaking experiment, revealing effects of inelastic scattering and spectral gaps on their dynamics through a solvable one-dimensional crystal model.

Contribution

It introduces a detailed numerical analysis of photoelectron propagation considering inelastic scattering and pulse duration effects, highlighting behavior near spectral gaps.

Findings

Wave packet moves with group velocity dE/dk far from spectral gaps.

Near spectral gaps, wave packet velocity exceeds group velocity during excitation.

Photoelectron dynamics are significantly affected by inelastic scattering and pulse duration.

Abstract

Laser-assisted photoemission from a solid is considered within a numerically exactly solvable one-dimensional model of a crystal. The effect of the inelastic scattering and of the finite duration of the pump pulse on the photoelectron dynamics is elucidated. The phenomenological result that the photoexcited wave packet moves with the group velocity dE/dk and traverses on average the distance equal to the mean free path is found to hold for energies far from the spectral gaps of the final state band structure. On the contrary, close to a spectral gap the photoelectron is found to move during the excitation by the pump pulse with a velocity higher than the group velocity.