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

A preliminary model is presented that describes the observed surface-enhanc ed electronic Raman scattering spectrum of self-assembled n-alkanethiol mon olayers 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 a lkane chain length and the temperature of the monolayer films.