Interlayer charge transfer in tin disulphide: Orbital anisotropy and temporal aspects

An investigation of the unoccupied electronic structure of the transition-metal dichalcogenide tin disulphide has been conducted using core-hole clock spectroscopy. Polarization-dependent x-ray absorption in the tender x-ray regime at the S K edge and maps of the resonant Auger spectra in the S KLL Auger kinetic energy range have been recorded. Supported with ab initio calculations of the unoccupied electronic structure, these allow us to relate resonances in the absorption cross section to excitations along various directions in the Brillouin zone. We observe anisotropy in the x-ray absorption cross section in polarization directions in plane and out of plane of the crystal. There is also anisotropy in the charge transfer dynamics as inferred from the coherent and noncoherent parts of the resonant Auger spectra. This approach can be generally used to interpret dynamics in unoccupied states, e.g., in layered structure or heterogenous interfaces.