Time-resolved Dark-field X-ray Microscopy

In the past decade, dark-field X-ray microscopy (DFXM), a full-field X-ray imaging technique, has emerged as a promising tool at synchrotron sources for mapping orientation, strain in deeply embedded structures. This technique has also been employed for studying in situ dynamic processes like dislocation motion as a function of temperature [1], structural transformation during phase transition in ferroelectric material [2], and so on. However, the pump-probe laser scheme incorporating the DFXM technique has not been reported yet. In this work, we demonstrate a time-resolved DFXM in the pump-probe scheme at Sector 6-IDC beamline using a 10-ns pulsed laser and the X-ray probe pulse obtained from the hybrid mode operation of the APS storage ring. 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.

1. Dresselhaus-Marais, Leora E., et al. "In situ visualization of long-range defect interactions at the edge of melting." Science Advances 7.29 (2021): eabe8311.

2. Ormstrup, Jeppe, et al. "Imaging microstructural dynamics and strain fields in electro-active materials in situ with dark-field x-ray microscopy." Review of Scientific Instruments 91.6 (2020): 065103.