"Time-resolved RIXS experiment with pulse-by-pulse parallel readout data collection using X-ray free electron laser"

H Lu: A. Gauthier, M. Hepting, A. S. Tremsin, A. H. Reid, P. S. Kirchmann, Z. X. Shen, T. P. Devereaux, Y. C. Shao, X. Feng, G. Coslovich, Z. Hussain, G. L. Dakovski, Y. D. Chuang & W. S. Lee; Scientific Reports, 12/17/20.

Additional Authors: A. Gauthier, M. Hepting, A. S. Tremsin, A. H. Reid, P. S. Kirchmann, Z. X. Shen, T. P. Devereaux, Y. C. Shao, X. Feng, G. Coslovich, Z. Hussain, G. L. Dakovski, Y. D. Chuang & W. S. Lee

Abstract:

Time-resolved resonant inelastic X-ray scattering (RIXS) is one of the developing techniques enabled by the advent of X-ray free electron laser (FEL). It is important to evaluate how the FEL jitter, which is inherent in the self-amplified spontaneous emission process, influences the RIXS measurement. Here, we use a microchannel plate (MCP) based Timepix soft X-ray detector to conduct a time-resolved RIXS measurement at the Ti L3-edge on a charge-density-wave material TiSe. The fast parallel Timepix readout and single photon sensitivity enable pulse-by-pulse data acquisition and analysis. Due to the FEL jitter, low detection efficiency of spectrometer, and low quantum yield of RIXS process, we find that less than 2% of the X-ray FEL pulses produce signals, preventing acquiring sufficient data statistics while maintaining temporal and energy resolution in this measurement. These limitations can be mitigated by using future X-ray FELs with high repetition rates, approaching MHz such as the European XFEL in Germany and LCLS-II in the USA, as well as by utilizing advanced detectors, such as the prototype used in this study.