Enhanced Infrared ATR Spectra of <i>O</i>-, <i>m</i>-, and <i>p</i>-Nitrobenzoic Acid with Ag Films

Abstract

The dependence of enhancement of the infrared bands by thin Ag films on the molecular structure of the organic compound was investigated. A different enhancement behavior for the three isomers—ortho-, meta-, and paranitrobenzoic acids—was observed and accounted for by structural features. The presence of the ionized species of the acids in the monolayer bonded to Ag was found, and the spectral features of the monolayer and bulk compound were compared. The splitting of the antisymmetric stretching band of the nitro group for metanitro benzoic acid strongly interacting with Ag was observed. The correlation of the morphology of the Ag surface to the magnitude of the achieved enhancement is discussed.