We have studied to establish an ultimate vibrational spectroscopy relevant for in situ characterization of single molecules at solid/liquid interfaces. The blinking of SERS (Surface Enhanced Raman Scattering) arises from thermal diffusion of adsorbed molecule between junction and other ordinary sites as evidenced from correlation between Raman and elastic scattering spectra in addition to temperature dependence and local field evaluation. Exploiting SERS of underlaid silver films, Raman images with ca. 50 nm in spatial resolution were obtained simultaneously with topography using chemically etched optical fibers under an attenuated total reflection configuration.