Examining electron-boson coupling using time-resolved spectroscopy

TL;DR

Time-resolved spectroscopy of a model electron-phonon system reveals that relaxation dynamics directly reflect the equilibrium self-energy, enabling quantitative extraction of electron-phonon coupling strength without complex assumptions.

Contribution

This work demonstrates that nonequilibrium pump-probe spectroscopy can directly measure electron-phonon coupling strength from relaxation dynamics.

Findings

Relaxation times are governed by the equilibrium self-energy.

Phonon frequency influences the timescale of recovery.

Quantitative electron-phonon coupling extraction is possible.

Abstract

Nonequilibrium pump-probe time domain spectroscopies can become an important tool to disentangle degrees of freedom whose coupling leads to broad structures in the frequency domain. Here, using the time-resolved solution of a model photoexcited electron-phonon system we show that the relaxational dynamics are directly governed by the equilibrium self-energy so that the phonon frequency sets a window for "slow" versus "fast" recovery. The overall temporal structure of this relaxation spectroscopy allows for a reliable and quantitative extraction of the electron-phonon coupling strength without requiring an effective temperature model or making strong assumptions about the underlying bare electronic band dispersion.