Coupled ESRF-EuXFEL proposal: Excited states of Co3O4 studied by static and time-resolved RIXS

The interest in charge transfer excitations in Transition Metal Oxides (TMOs) is due to the photocatalytic and photovoltaic applications of these materials. Co3O4 is especially intriguing for showing different relaxation pathways when exciting at two different wavelengths, faster at 400 nm than at 800 nm. Static and time-resolved RIXS experiments, jointly made, can provide insight on these different time scales and on the microscopic mechanisms underlying. We propose to measure at ID32 medium and high resolution static RIXS spectra of a Co3O4 single crystal, to obtain a definitive assignment of the excitations in the 0.5-3.0 eV range and to study electron-phonon coupling for the dominant A1g. Together with future trRIXS measurements to be proposed at SCS@EuXFEL, those results will clarify the role of Co3+ sites, in defining the electronic properties of this intriguing material and the microscopic origin of different photoexcited states lifetimes.