Vibrational sum-frequency generation (VSFG) is a nonlinear spectroscopic method widely used to investigate the molecular structure and dynamics of surface systems. However, in far-field observations, the spatial resolution of this method is constrained by the diffraction limit, which restricts its ability to resolve molecular details in inhomogeneous structures smaller than the wavelength of light.
To address this limitation, researchers, Atsunori Sakurai, Shota Takahashi, Tatsuto Mochizuki, and Toshiki Sugimoto, Institute for Molecular Science (IMS), NINS, developed a tip-enhanced VSFG (TE-SFG) spectroscopy system based on scanning tunneling microscopy (STM). Using this system, the team detected VSFG signals from molecules adsorbed on a gold substrate under ambient conditions.
The research is published in the journal Nano Letters.