Study of surface-enhanced infrared spectroscopy - 2. Large enhancement achieved through metal-molecule-metal sandwich configurations

In this paper we report a versatile and effective strategy to attain strong surface-enhanced infrared absorption by employing a sandwich system consis ting of metal island films and self-assembled monolayers (SAMs) of 4-pyridi nethiol, The observed larger enhancement factor stems from coupling of the electric fields induced by excitation of the surface plasmon resonance of t he overlayer and underlayer Au island films, and from enhanced chemical int eractions of the Au island films and the pyridine molecule in the sandwiche d structures, compared to the corresponding SAM-Au configuration. (C) 2001 Academic Press.