ENHANCED INFRARED-ABSORPTION OF THIOUREA ADSORBED ON A ROUGH SILVER SURFACE

Thin films of different thicknesses, made by thiourea molecules deposi ted on a flat silver surface roughened by treatment with chemical etch ing solutions, have been studied by infrared reflection-absorption spe ctroscopy. A significant enhancement (of the order of several hundreds ) of the infrared absorption cross-section of the thiourea molecules h as been found. In agreement with the surface-enhanced Raman spectrosco py results for the same films, it has been found that the main enhance ment is associated with the first layer of thiourea molecules chemisor bed on the silver surface.