Spectroscopic investigation of S–Ag interaction in ω-mercaptoundecanoic acid capped silver nanoparticles

This paper deals with the synthesis of ω-mercaptoundecanoic acid (MUA) capped silver nanoparticles (NPs) with an average size of 15 nm by citrate reduction technique and spectroscopic investigation of S–Ag interaction. We have studied the interaction of thiol with silver NPs in aqueous medium by employing UV–vis, Raman, FT-IR, and photoluminescence spectroscopy. The shifting of silver surface plasmon band in the UV–vis spectra shows the stabilization of the silver nanoparticles by MUA. The disappearance of S–H stretching in both the FT-IR and Raman spectra and the shifting of the NMR signals of the protons in close proximity to the metal center supported the existence of the S–Ag interaction in MUA capped silver NPs. The morphology of the thiol protected silver NPs was investigated by transmission electron microscopy (TEM) and was found to be distinct and spherical entities.