Raman and reflection spectroscopy of H 2O covered coldly deposited silver films

Abstract

Both Raman and reflection spectroscopy show that H 2O penetrates the porous film structure between 120 and 150 K, the temperature of thermal desorption is increased by about 15–20 K with respect to smooth silver. The Raman intensity increases by a factor of 3–6, reaching the relative low enhancement of 3–4 orders of magnitude. The anomalous optical absorption is red-shifted by water adsorption analogous to the splitted surface plasmon structure, which indicates an electromagnetic resonance as origin of the anomalous optical absorption.