High-pressure surface-sensitive techniques

In situ studies of catalytic reactions have also been a prime focus of our group. The high-pressure spectroscopic technique used in our research is polarization modulation IR reflection absorption spectroscopy (PM-IRAS). Like SFG, PM-IRAS is a highly surface-sensitive technique that yields vibrational information about adsorbed surface species. Unlike SFG, however, PM-IRAS... 

The dilemma is thus investigations of real catalysts under relevant conditions by in situ techniques give little information on the surface of the catalyst, while techniques that are surface sensitive can often only be applied on model surfaces under vacuum. Bridging the gap between UHV and high pressures and between the surfaces of single crystals and of real catalysts is therefore an important issue in catalysis. 

The variety of sampling methods available in spectrofluorimetry makes it a very versatile technique. The most frequent mode of sample presentation is as a dilute solution, although gases, suspensions, and solid surfaces can also be examined. Combinations of spectrofluorimetry with thin-layer chromatography and high pressure liquid chromatography are particularly advantageous for sensitive and selective detection offluorophores. 

In the future we will see the development of more and more sophisticated surface analytical techniques capable of analyzing a variety of surface types under high-pressure reaction conditions. Eventually this will eliminate the complications of sample transfer into UHV described here. At the same time, more sensitive detection schemes for gaseous products will appear, as will reproducible recipes for preparation of homogeneous surfaces of complex materials. All these developments will facilitate the... 

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