Infrared and Raman spectra of 4-cyanobenzoic acid on powdered silver

Abstract

We have attempted to record the infrared and Raman spectra of 4-cyanobenzoic acid (4CBA) adsorbed on 2-mu m-sized silver particles. The diffuse reflectance infrared Fourier transform (DRIFT) spectrum taken for the sample was little different from the reflection-absorption infrared (RAIR) spectrum taken for the same molecules on vacuum-evaporated thick silver films, suggesting that the usual surface selection rule should be applicable even to the surface of fine metal particles. The Raman spectrum of 4CBA on powdered silver was a surface-enhanced Raman (SER) spectrum, exhibiting little difference from that taken on vacuum-evaporated thin, rough silver films. Thus, the commercially available powdered silver seemed to be an efficient substrate for the infrared and Raman spectroscopic characterization of molecular adsorbates prepared in a similar way on silver surfaces. (C) 1999 Elsevier Science B.V. All rights reserved.