Toward Gold Nanoparticle Dimers for Single-Molecule Surface-Enhanced Raman Scattering W. E. Moerner, Department of Chemistry, Stanford University, Stanford, CA 94305 Single molecule Surface-Enhanced Raman Scattering (smSERS) is an extremely sensitive method for measuring trace chemical species. In order to control this effect, it is useful to study a model system consisting of two 250 nm gold nanoparticles linked by a single biphenyldithiol molecule. (Synthesized in the C. Chidsey lab) S S Exciting single dumbbells with 830nm laser light allowed the preliminary observation of Raman scattering spectra from individuals (right, synthesized at ultra-low linker concentrations, i.e. 1:5 linker molecule to nanoparticle ratio). The observation of spectral diffusion in the spectra along with the ultralow dithiol concentration during synthesis suggests that the Raman signal originates from a single molecule. Unfortunately, the synthesis of these structures depends upon surface ligands and is difficult to control.