Stroboscopic Tests for Thermalization of Electrons in Pump/Probe Experiments

TL;DR

This paper proposes a method using stroboscopic tests to assess electron thermalization in pump/probe experiments by comparing effective temperatures of fermions and bosonic modes, providing a more direct measure of thermalization.

Contribution

It introduces a novel approach to evaluate electron thermalization by measuring and comparing effective temperatures of fermions and bosons, bypassing the limitations of Fermi-Dirac fitting.

Findings

Effective temperature comparison quantifies thermalization.

Photoemission and Raman scattering enable direct temperature measurements.

Difference in temperatures indicates proximity to thermal equilibrium.

Abstract

One of the goals of pump/probe spectroscopies is to determine how electrons relax after they have been driven out of equilibrium. It is challenging to determine how close electrons are to a thermal state solely by fitting their distribution to a Fermi-Dirac distribution. Instead, we propose that one compare the effective temperatures of both fermions and collective bosonic modes (derived from the fermions) to determine the distance from a thermal state. Measurements of effective fermionic and bosonic temperatures can be achieved directly via photoemission and nonresonant Raman scattering. Their difference quantifies the distance from thermal equilibrium.