XRM 2026 Experimental data

TIME-RESOLVED DARK-FIELD X-RAY MICROSCOPY

Revealing Defect-Mediated Lattice Dynamics with Time-Resolved Dark-Field X-ray Microscopy

Time-resolved DFXM images how a laser-induced strain field propagates and undergoes mode conversion upon interacting with defects.
The high penetration depth of X-rays enables subsurface wave components to be tracked throughout the bulk.

View supplementary figures ↓ View DFXM movies ↓
Seong Gook KimPOSTECH · Max Planck POSTECH/Korea Research Initiative

EXPERIMENTAL DATA

Movies

01-1

Experimental data movie

All pump–probe delay measurements were interleaved with periodic intact-state measurements to verify reversible sample recovery and measurement reproducibility.

01-2

Annotated elastic-wave propagation

Blue arrows indicate the longitudinal strain wave propagating along the depth direction, while red arrows indicate the transverse elastic wave propagating in plane.

01-3

Larger-beam case: extended field of view

A larger beam size enables a broader sample region to be probed. Consistent longitudinal and transverse wave responses are also observed near the dislocation on the right; the red arrows specifically mark the transverse in-plane component.

01-4

Other case: weak-contrast dislocation

The same in-plane transverse strain-wave response is observed at a weak-contrast dislocation located at or very near the surface from 1,000 to 6,000 ps. The red arrow marks its propagation.

SUPPLEMENTARY MATERIAL

Supplementary figures

Swipe through the analysis—from ultrafast excitation to strain-wave propagation.

Ge dislocation geometries alongside their corresponding DFXM difference images
01 · DEFECT CONTRAST

Ge {111}⟨110⟩ dislocations

In our experimental geometry, the DFXM contrast and its characteristic image shape depend on the dislocation type and orientation. The difference images are obtained by subtracting the perfect-crystal DFXM image from the defect-containing case.

Simulated DFXM response to lateral translation of a localized strain field Simulated DFXM response to inward translation of a localized strain field
02 · DFXM SIMULATION

Simulated DFXM response to strain translation

For lateral and inward translations, simulations show how a moving strain field—not a moving defect—changes the DFXM contrast, with the extracted shifts matching geometric predictions.

Calculated electron and lattice temperatures as a function of time
03 · TTM SIMULATION

Electronic and lattice temperature response

COMSOL two-temperature-model simulation of ultrafast laser excitation in germanium, showing rapid electron heating followed by electron–phonon energy transfer to the lattice.

Stacked profiles annotated with in-plane and out-of-plane wave components and the initial defect position
04 · OVERVIEW

Overall DFXM dynamics

Stacked DFXM profiles show the overall evolution of the out-of-plane longitudinal and in-plane transverse strain-wave components.