Pump-Flow-Probe X-Ray Absorption Spectroscopy as a Tool for Studying Intermediate States of Photocatalytic Systems.
A new setup for pump-flow-probe X-ray absorption spectroscopy has been implemented at the SuperXAS beamline of the Swiss Light Source. It allows recording X-ray absorption spectra with a time resolution of tens of microseconds and high detection efficiency for samples with sub-mM concentrations. A continuous wave laser is used for the photoexcitation, with the distance between laser and X-ray beams and velocity of liquid flow determining the time delay, while the focusing of both beams and the flow speed define the time resolution. This method is compared with the alternative measurement technique that utilizes a 1 kHz repetition rate laser and multiple X-ray probe pulses. Such an experiment was performed at beamline 11ID-D of the Advanced Photon Source. Advantages, limitations and potential for improvement of the pump-flow-probe setup are discussed by analyzing the photon statistics. Both methods, with Co K-edge probing were applied to the investigation of a cobaloxime-based photo-catalytic reaction. The interplay between optimizing for efficient photoexcitation and time resolution as well as the effect of sample degradation for these two setups are discussed.
Lund University, Lund, 22100, Sweden ; Paul Scherrer Insitute, Villigen, 5232, Switzerland.
Grigory
G
Smolentsev
Research center for nanoscale structure of matter, Southern Federal University, Rostov-on-Don, 344090, Russia.
Alexander
A
Guda
X-ray Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA.
Xiaoyi
X
Zhang
Department of Physics, Danish Technical University, Copenhagen, Denmark.
Kristoffer
K
Haldrup
Laboratory of Chemistry and Biology of Metals, CEA,CNRS, University Joseph Fourier, Grenoble, France.
Eugen
E
Andreiadis
Laboratory of Chemistry and Biology of Metals, CEA,CNRS, University Joseph Fourier, Grenoble, France.
Murielle
M
Chavarot-Kerlidou
Lund University, Lund, 22100, Sweden.
Sophie E
SE
Canton
Paul Scherrer Insitute, Villigen, 5232, Switzerland.
Maarten
M
Nachtegaal
Laboratory of Chemistry and Biology of Metals, CEA,CNRS, University Joseph Fourier, Grenoble, France.
Vincent
V
Artero
Lund University, Lund, 22100, Sweden.
Villy
V
Sundstrom
LITR XAS; Photocatalysis; Time-resolved spectroscopy; XANES; XTA; cobaloxime; pump-probe