Acoustic response of a laser-excited polycrystalline Au-film studied by ultrafast Debye-Scherrer diffraction at a table-top short-pulse X-ray source

TL;DR

This study investigates the ultrafast acoustic response of a polycrystalline gold film using time-resolved X-ray diffraction with a table-top laser-driven X-ray source, revealing strain dynamics consistent with theoretical models.

Contribution

It demonstrates the use of ultrafast Debye-Scherrer diffraction at a table-top source to measure transient strain in a polycrystalline film, combining experimental and theoretical analysis.

Findings

Good agreement between experimental data and two-temperature model

Transient strain shifts observed in multiple Bragg peaks

Validation of uni-axial strain propagation assumption

Abstract

The transient acoustic response of a free-standing, polycrystalline thin Au film upon femtosecond optical excitation has been studied by time-resolved Debye-Scherrer X-ray diffraction using ultrashort Cu K$_{\alpha}$ X-ray pulses from a laser-driven plasma X-ray source. The temporal strain evolution has been determined from the transient shifts of multiple Bragg diffraction peaks. The experimental data are in good agreement with the results of calculations based on the two-temperature model and an acoustic model assuming uni-axial strain propagation in the laser-excited thin film.