Raman scattering from 1,3-propanedithiol at a hot spot: Theory meets experiment

Using tools of density functional theory, we compute the Raman spectra of 1,3-propanedithiol (PDT) isolated in the gas phase, solvated in methanol, tethered either to the face or vertex of a tetrahedral Ag20 cluster, and bridging two Ag20 clusters. The derived molecular polarizability derivative tensors are used to simulate molecular orientation-dependent Raman scattering, achieved by rotating the polarizability tensors relative to vector components of the incident/scattered radiation fields. Our framework is weighed against SERS experiments which probe the optical response at a hotspot formed by an Ag surface coated with PDT and a single 60-nm Ag nanosphere.