Crystals (Dec 2020)

The Effect of Intensity Fluctuations on Sequential X-ray Photon Correlation Spectroscopy at the X-ray Free Electron Laser Facilities

  • Yue Cao,
  • Dina Sheyfer,
  • Zhang Jiang,
  • Siddharth Maddali,
  • Hoydoo You,
  • Bi-Xia Wang,
  • Zuo-Guang Ye,
  • Eric M. Dufresne,
  • Hua Zhou,
  • G. Brian Stephenson,
  • Stephan O. Hruszkewycz

DOI
https://doi.org/10.3390/cryst10121109
Journal volume & issue
Vol. 10, no. 12
p. 1109

Abstract

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How materials evolve at thermal equilibrium and under external excitations at small length and time scales is crucial to the understanding and control of material properties. X-ray photon correlation spectroscopy (XPCS) at X-ray free electron laser (XFEL) facilities can in principle capture dynamics of materials that are substantially faster than a millisecond. However, the analysis and interpretation of XPCS data is hindered by the strongly fluctuating X-ray intensity from XFELs. Here we examine the impact of pulse-to-pulse intensity fluctuations on sequential XPCS analysis. We show that the conventional XPCS analysis can still faithfully capture the characteristic time scales, but with substantial decrease in the signal-to-noise ratio of the g2 function and increase in the uncertainties of the extracted time constants. We also demonstrate protocols for improving the signal-to-noise ratio and reducing the uncertainties.

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