Surface enhanced Raman scattering of a single molecular junction.

The characterization of a single molecular junction is essential to investigate and utilize the single molecular junction in single molecular devices. Vibration spectroscopy is a promising technique for characterizing the atomic structure of the single molecular junction. In this review paper, we describe the surface-enhanced Raman scattering (SERS) as a vibration spectroscopy of a single molecular junction. A strong electric field is formed in the nanogaps in the single molecular junction, which enhances the intensity of the Raman signal. The Raman signal from a single molecule in the nanogap is selectively observed thanks to the strong electric field. Simultaneous SERS and conductance measurements provide information of the geometric structure of the single molecular junction, which can clarify the single molecular dynamics.