Enhancement of Raman Scattering of 1,4-Benzenedithiol by CdS Nanoparticles Assembled on a Silver Surface

CdS nanoparticles were assembled on the smooth surface of a piece of silver by using 1,4-benzenedithiol as coupling molecules. The SEM and resonance Raman spectroscopic characterizations demonstrate that the nanosized structure of CdS was still preserved upon assembly, and a two-dimensional structure of CdS nanoparticles was formed on the substrate surface. The FT-Raman spectra indicate that 1,4-benzenedithiol was coupled between CdS nanoparticles and the silver surface with a tilted orientation. The Raman scattering of 1,4-benzenedithiol was substantially enhanced by the assembled CdS nanoparticles, probably due to the alteration of the polarizability of 1,4-benzenedithiol and the electromagnetic interaction between the dipoles of the CdS particle with its image in the metal substrate.