We have been pioneering the application of RIXS to transient states using x-ray free electron lasers.
Figure 1: An illustration of time-resolved RIXS. See M. P. M. Dean et al., Nature Materials 15, 601–605 (2016) for more details.
Ultrafast dynamics of spin and orbital correlations in quantum materials: an energy-and momentum-resolved perspective
Philosophical Transactions of the Royal Society A