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The structure of monolayers and multilayers of V2O5 supported on TiO2 has been investigated by laser Raman spectroscopy. For the catalyst prepared by a single impregnation, disordered polymeric arrays of sixfold‐coordinated vanadium ions are detected. Second impregnation increases the number of Vv centers anchored on the support but does not create new types of structure in detectable amounts. In the third impregnation step additional layers of V2O5 are immobilized on top of the first layer, as evidenced by characteristic Raman bands at ∼996 cm−1 and 285 cm−1. The intensity of these bands from higher layers increases after the fourth impregnation; at this stage the highest specific activity of the supported catalyst for selective catalytic reduction of NO is achieved. The above conclusions are confirmed by FTIR measurements, which reveal structural differences between the vanadia species immobilized in the first and subsequent layers.

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A cooled multichannel detector has been developed that is based on a second-generation image intensifier tube and a Reticon photodiode array. The sensitivity of the device is characterized and discussed in terms of the limiting noise sources. For use in Raman spectroscopy, the detector has been optically matched to a triple spectrograph. Signal-to-noise ratios obtained with this detection system are compared with those of typical photon counting instruments. The required integration time (∼1000 s) and substrate properties to record unenhanced Raman signals from an adsorbed molecular monolayer on a surface are discussed.