Modeling time-resolved x-ray spectroscopy from the atomic orbital ground state up*

X-ray edge spectroscopies have been a key method to determine ground and excited state properties of quantum materials with atomic specificity. With the advent of next generation x-ray free-electron lasers (XFEL), pump-probe x-ray spectroscopies such as time-resolved x-ray absorption (tr-XAS) and time-resolved resonant inelastic x-ray scattering (tr-RIXS) have the potential to shed light on these properties in the time domain.

I will present tr-XAS and tr-RIXS modeling, obtained using a time-resolved, full atomic multiplet, charge transfer Hamiltonian and many-body Hilbert space generalized for a central transition metal ion surrounded by a ligand cage in square planar geometry. The time dynamics for two representative materials - CuO and NiO - frame the discussion about insights that can be obtained from pump-probe spectroscopies. I will highlight how our approach can help to shape experimental design as new capabilities become available at XFELs.