Distance dependence of surface enhanced Raman scattering probed by alkanethiol self-assembled monolayers

Abstract

A distance dependence study of the surface enhanced Raman effect has been performed using alkanethiol CH₃(CH₂)_nSH self-assembled monolayers on top of rough silver surfaces. We found a decrease of the enhancement signal of the CH₃ heads by a factor of 2, increasing the CH₃–surface distance from 0.8 to 2.5 nm (n=5–17) and a distance function compatible with the known Gersten and Nitzan theory on the electromagnetic enhancement. Parameters obtained by an experimental data fit agree with previous observations on silver surface morphology.