A computational study on surface-enhanced Raman spectroscopy of para-substituted Benzenethiol derivatives adsorbed on gold nanoclusters

We presented a computational study on para-substituted Benzenethiol (x-BT, x = H, F, Cl, Br, OH, SH, SeH, NH₂, CH₃) derivatives interacting with gold cluster for chemical effects related to surface-enhanced Raman spectroscopy (SERS). Density functional theory (DFT) calculations were performed on a series of bridge-type and vertex type x-BT/Au₁₃ complexes for geometric, electronic and excitation properties to determine the key factor in spectral enhancement. Results indicated that off-resonance enhancement factors of bridge-type and vertex-type complexes exhibited different dependency on substitutions, which was greatly influenced by molecule-cluster transitions instead of properties such as interaction energy and charge transfer due to same origination for off-resonance and resonance chemical enhancement.