Physical Origins of Chemical Enhancement of Surface-Enhanced Raman Spectroscopy on a Gold Nanoparticle-Coated Polymer

Chemical enhancement of surface-enhanced Raman spectroscopy was investigated using a gold nanoparticle (AuNP)-coated polymer substrate, and an enormous b(2)-mode signal enhancement arose from the evaporation-induced reorientation of 4-aminobenzenethiol molecules adsorbed onto the AuNP surface. The dynamic analysis of time-dependent increases of chemically enhanced Raman signals enables us to measure the charge coupling strengths between molecules and metal at varying surface environments and to differentiate the solvent drying-mediated coupling effect with a long-term stability from photogenerated, metastable charged states showing a relatively rapid signal decay.