The aim of the project is the development and application of time-resolved X-ray absorption and X-ray emission methods to characterize intermediate state of catalysts and photo-excited states of metal complexes.
Within this project we use X-ray absorption spectroscopy to investigate local atomic and electronic structure with time resolution, for example to catch intermediate state of catalysts and excited state of photosensitizers. There are a few advantages of X-ray absorption spectroscopy:
- Selectivity to the type of atoms allows to probe individual components of photocatalytic mixtures.
- X-ray absorption near edge structure (XANES) is sensitive to the 3D arrangements of atoms around the absorbing center at the distances up to ~4.5 Angstroms
- Time-resolved methodology allows to track changes in the system triggered by light and to separate them from slow processes that can occur simultaneously in the system.
In combination with X-ray emission spectroscopy the method allows to get complete picture about the electronic structure changes, in particular, spin and oxidation state of 3d metal centers.
The pump-probe project is hosted at the SuperXAS beamline of Swiss Light Source (SLS) synchrotron (Paul Scherrer Institut, Villigen, Switzerland). Currently we extend the project to the pump-probe XAS in the tender X-ray range at Phoenix beamline and to the pump-probe XES with pink beam excitation at MicroXAS and SuperXAS. The setups at SuperXAS are typically used in the time range 100 ns - 1ms and in more specific cases can be also used for experiments with 100 ps resolution. Faster processes in the time range 1 -50 ps we investigate at X-ray free electron lasers, in particular at Alvra beamline of SwissFEL and FXE instrument of European XFEL.