The effect of self-assembled nanometric spacers on surface enhanced Raman spectra of terthiophene ultrathin films

Self-assembled monolayers (SAMs) of different length have been built onto silver surfaces suitable for surface enhanced Raman (SER) effect. The analysis of the surface enhanced Raman spectra as a function of the monolayer thickness allowed to study SER effect by changing the distance in a nanometric way. In this work, we present a case of distance dependence in which SER spectra of terthiophene are studied for molecules deposited onto SAMs previously adsorbed on roughened silver. Each spacer is able to inhibit the oligomerization of terthiophene already observed by us, when the molecules are adsorbed onto bare silver. It will also be shown how the spectral features of the deposited terthiophene gradually vary by changing the spacer thickness from 0.8 to 2.5 nm.