Combining XAFS with Raman spectroscopy enables studies of the correlation between the structure of catalytically active sites and activity/selectivity information. XAFS provides information about the structural features and electronic properties of the catalysts. Raman spectroscopy provides fundamental molecular level information about the catalyst surface structure and reactive surface intermediates under practical reaction conditions.

The Raman system implemented at the SCC is a portable fiber optic system which can be used at all beam lines X18A, X18B and X19A.The system includes 532 nm miniature laser, a flexible fiber optic bifurcated Raman probe with lens assembly for directly measuring solid or liquid samples at high temperature and a Uv Vis CCD detector 200-1000nm, soft cooled -20°C.Custom step ND filter attenuator for adjusting laser power allows laser power to be attenuated for 0-100 fold continuously.

Raman measurements are carried out with excitation laser focused down into a round spot ~3µm diameter and the signals are analyzed with a CCD detector. The Raman spectrograph spectral range is from 50-3200cm-1 with spectral resolution of 6-7cm-1.Flexible fiber optic Raman probe accommodates in any reactor cell of choice and positioned very comfortable in any dimension and making it possible to combine with more than two complementary techniques with in situ measurements combined with Residual gas analyzer.

References describing development and application of combined XAFS-Raman spectroscopy capabilities:

1) A. Patlolla, Ph. Baumann, W. Xu, S. Senanayake, J. A. Rodriguez, A. I. Frenkel
Characterization of metal-oxide catalysts in operando conditions by combining X-Ray Absorption and Raman spectroscopies in the same experiment
Top. Catal. 56, 896-904 (2013)

2) A. Patlolla, E. V. Carino, S. Ehrlich, E. Stavitski, A. I. Frenkel
Application of operando XAS, XRD and Raman Spectroscopy for phase speciation in water gas shift reaction catalysts
Invited article, ACS Catalysis 2, 2216-2223 (2012)