Temperature effect on the SERS signature of p-aminothiophenol: a new evidence for the production of p,p'-dimercaptoazobenzene on metallic nanostructures.

We investigated the effect of the temperature of the plasmonic substrate on the surface enhanced Raman scattering of p-aminothiophenol adsorbed onto a particulate film of gold nanoparticles-decorated polystyrene nanospheres. The results demonstrated that temperature induces important modifications in the overall spectral signature of the charge transfer bands, which are consistent with the generation of a new molecular species. Moreover, the analysis of the shape of the vibrational band at 1078 cm(-1) assigned to the >C-S mode, which is enhanced by electromagnetic mechanism, reveals the co-existence of two distinct bands at 1071 and 1078 cm(-1), assignable to p,p'-dimercaptoazobenzene and p-aminothiophenol, respectively.