Spectroscopic set-up for simultaneous UV-Vis/(Q)EXAFSin situandin operandostudies of homogeneous reactions under laboratory conditions

Abstract

A novel experimental set-up for in operando studies of homogeneous catalyzed reactions under laboratory conditions has been developed and tested. It combines time-resolved X-ray absorption spectroscopy with UV/Vis spectroscopy. The reaction solution is stirred in a vessel and pumped in a circle by a peristaltic free gear-wheel through a measurement cell. The X-ray and UV/Vis beams probe the same sample volume of the cell orthogonally. Reactants can be added to the reaction mixture in the course of the measurements and a defined gas atmosphere can be adjusted up to a pressure of 10 bar. The in situ reduction of cerium(IV) ammonium nitrate to cerium(III) by isopropanol is studied as a test reaction with quick-XANES and UV/Vis measurements with a time resolution of 60 s and 1 s, respectively.

HERFD-XAS and valence-to-core-XES: new tools to push the limits in research with hard X-rays?

“…Simultaneous combinations can be frequently found for conventional XAS, e.g. with IR, 101 Raman 1,102 and UV/Vis 1,68,103 spectroscopy. 104 Although it is in principle possible to combine HERFD-XANES and V2C-XES with other methods, the geometric requirements are slightly different, and still such combinations are rare.…”

“…Although in solid samples also radiation damage is observed, they can be more simply coped with by moving the solid sample in the beam. For liquid sample cells as used in studies on homogeneous reactions, 1,2,68 only moving the cell in the beam is not enough due to the large energy impact on the liquid. Therefore a rather large volume of the solution sample has to be moved continuously.…”

Determination of the electronic and structural configuration of coordination compounds by synchrotron-radiation techniques

“…Besides the obvious benefit of a significant reduction in the acquisition time, energy dispersive EXAFS is characterized by the absence of any movement of the optics during the spectrum acquisition (guarantying a potentially high beam stability) and by the extremely small and stable horizontal focal spot that allows this setup to be potentially used for space resolved experiments also [438,[442][443][444]. Both QEXAFS and energy dispersive EXAFS methods have been successfully integrated in multi-technique setups for in situ and operando characterization [76,147,155,341,426,[445][446][447][448][449][450][451][452][453][454][455][456][457][458][459][460], where for instance EXAFS is combined to XRPD or XRS methods for a simultaneous long-and short-range structural determination [64,155,276,461] (see also Section 2.6.1), or to a suite of non-X-ray spectroscopic techniques, including IR, UV-Vis and mass spectroscopies [283,286,426,[459][460][461][462][463][464][465][466][467]…”

François Garin: Pioneer work in catalysis through synchrotron radiation

“…We can see clearly the different parts of the experimental set-up with a device dedicated to increase the temperature of the samples to 700°C. An examination of the literature shows that several devices to control the gas mixture that goes through the catalysts have been developped [117][118][119][120][121][122][123][124][125][126][127][128].…”