Pump-probe Dark-field X-ray Microscopy

TL;DR

This paper demonstrates a pump-probe dark-field X-ray microscopy technique at APS, revealing laser-induced thermal and acoustic phenomena in Germanium crystals with nanosecond resolution, enabling new insights into dynamic material processes.

Contribution

It introduces a novel pump-probe DFXM method combining laser pulses with X-ray imaging to observe rapid thermal and acoustic effects in solids.

Findings

Thermal decay in Germanium matches theoretical models.

Laser-induced lattice deformation causes observable thermal strain.

On-the-fly imaging of acoustic wave propagation was achieved.

Abstract

A pump-probe dark-field X-ray microscopy (DFXM) experiment was carried out at the Advanced Photon Source (APS) with nanosecond drive laser pulses and hybrid mode X-ray probe pulses. We observe a thermal decay due to laser-induced heat diffusion in a Germanium single crystal which matches the theoretical prediction. The single pulse DFXM imaging in combination with the laser-pump X-ray probe method could reveal thermal strain formation and propagation of the acoustic wave "on-the-fly" generated by a laser-induced lattice deformation. This will open a new avenue of materials research on laser-induced dynamic phenomena in solids at sub-nanosecond time scales.