Speaker
Grigory Smolentsev
(Paul Scherrer Institut)
Description
A new setup for time-resolved X-ray absorption measurements in the microsecond time range has been developed at SuperXAS beamline of SLS. It consists of the nanosecond laser (~1W average power, 447 nm or 671 nm wavelength, 5-50 kHz repetition rate), detection system based on avalanche photo diodes that is optimized to measure signals of dilute samples (with concentration ~1mM) and data acquisition system that allows to record a full kinetic information (arrival time of all fluorescent X-ray photons relative to the laser pulse).
The method has been applied to investigate intermediate state of multicomponent photocatalytic system that evolves hydrogen. Transient spectra corresponding to the intermediate states of Co-based catalyst cobaloxime has been recoded and formation of Co(I) intermediate has been observed. We have not observed any signatures of the second reaction pathway proposed in the literature that corresponds to the Co(II) oxidation. The structure of Co(I) intermediate has been clarified on the basis of combination of transient XANES fitting and DFT calculations.
Primary author
Grigory Smolentsev
(Paul Scherrer Institut)
Co-authors
Dr
Alexander Guda
(Southern Federal University)
Andreiadis Eugen
(CEA)
Christophe Frieh
(Paul Scherrer Institute)
Flavio Zamponi
Gaudenz Jud
(Paul Scherrer Institut)
Jeroen van Bokhoven
(Paul Scherrer Institut)
Dr
Maarten Nachtegaal
(Paul Scherrer Institut)
Markus Janousch
(Paul Scherrer Institut)
Murielle Chavarot-Kerlidou
(CEA)
Dr
Vincent Artero
(CEA)
