@misc{9249042,
  abstract     = {{Precise determination of the time of simultaneous incidence of laser pump and X-ray probe pulses is essential for ultrafast X-ray diffraction experiments. This work investigates the use of diffuse scattering from the phase-change material Ge2Sb2Te5(GST) as a timing tool for pump-probe measurements at the FemtoMAX beamline at MAX IV Laboratory.

A complete data analysis pipeline was developed to process time-resolved powder diffraction data. Individual detector images were sorted into pump-probe delay bins using the jitter monitors at FemtoMAX, azimuthally integrated using the pyFAI software package, and combined to produce time-resolved scattering profiles.

Measurements obtained during three experimental campaigns reproduced the characteristic ultrafast increase in diffuse scattering intensity following femtosecond laser excitation of GST. By combining data from multiple delay scans, the intensity increase was resolved to occur within 70 fs, consistent with previous measurements at FemtoMAX. The impact of laser fluence and sample temperature on the diffuse scattering response was also investigated, with the signal becoming difficult to resolve at low excitation fluences.

These results demonstrate that transient diffuse scattering from GST provides a reproducible marker of time zero for ultrafast X-ray diffraction experiments in a variety of experimental conditions. The analysis framework developed in this work provides a reliable methodology for processing future pump-probe diffraction measurements, and supports the continued use of GST as a time-zero monitor at FemtoMAX.}},
  author       = {{Dolan, Sally}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{LRAP, Lund Reports on Atomic Physics}},
  title        = {{Transient diffuse scattering in GeSbTe (GST) as a timing tool for ultrafast X-ray diffraction}},
  year         = {{2026}},
}