Dynamics of Nanoscale Phase Decomposition in Laser Ablation

TL;DR

This study uses femtosecond X-ray pulses to observe nanoscale phase decomposition in gold films during laser ablation, providing new insights into the highly nonequilibrium processes involved.

Contribution

It presents the first direct experimental observation of nanoscale phase decomposition dynamics during femtosecond laser ablation using time-resolved small angle scattering.

Findings

Confirmed transient heterogeneous density distributions in ablation plumes.

Validated molecular dynamics simulations with experimental data.

Abstract

Femtosecond laser ablation is a process that bears both fundamental physics interest and has wide industrial applications. For decades, the lack of probes on the relevant time and length scales has prevented access to the highly nonequilibrium phase decomposition processes triggered by laser excitation. Enabled by the unprecedented intense femtosecond X-ray pulses delivered by an X-ray free electron laser, we report here results of time-resolved small angle scattering measurements on the dynamics of nanoscale phase decomposition in thin gold films upon femtosecond laser-induced ablation. By analyzing the features imprinted onto the small angle diffraction patterns, the transient heterogeneous density distributions within the ablation plume as obtained from molecular dynamics simulations get direct experimental confirmation.