Surface-enhanced electronic Raman scattering from self-assembled alkanethiol monolayers on gold surfaces

A preliminary model is presented that describes the observed surface-enhanced electronic Raman scattering spectrum of self-assembled n-alkanethiol monolayers on roughened Au surfaces. At room temperature, a series of intense resonance Raman spectral lines, superimposed on the normal surface-enhanced Raman vibrational spectrum, are produced when monolayers of CH3(CH2)(m)SH (m = 8 to 17) are illuminated with laser radiation between 630 and 740 nm. We describe the effects of isotopic substitution, and of varying both the alkane chain length and the temperature of the monolayer films.