Two-dimensional surface enhanced Raman mapping of differently prepared gold substrates with an azobenzene self-assembled monolayer

An azobenzene self-assembled monolayer (SAM) was used to obtain the two-dimensional surface-enhanced Raman scattering (SERS) maps of gold substrates, which were prepared by electrochemical roughening and colloidal Au nanoparticle assembling, respectively. The Raman maps thus obtained showed that the lateral distribution of SERS intensity varies to a significant extent over the substrate surface. Especially, the nanoparticle substrate has a more homogeneous distribution of SERS enhancement factors than that of the electrochemically roughened one, which are believed to reflect the different morphology of these two substrates.