Tip-Enhanced Sum Frequency Generation for Molecular Vibrational Nanospectroscopy
Abstract
Vibrational sum frequency generation (SFG) is a nonlinear spectroscopic technique widely used to study the molecular structure and dynamics of surface systems. However, the spatial resolution achieved by far-field observations is constrained by the diffraction limit, obscuring molecular details in inhomogeneous structures smaller than the wavelength of light. To overcome this limitation, we developed a system for tip-enhanced SFG (TE-SFG) spectroscopy based on a scanning tunneling microscope. We successfully detected vibrational TE-SFG signals from adsorbed molecules on a gold substrate under ambient conditions. The phase analysis of interferometric SFG spectra provided information on molecular orientation. Furthermore, the observed TE-SFG signal was confirmed to originate from a highly localized region within a gap between the tip apex and the sample substrate. This method offers a novel platform for nonlinear optical nanospectroscopy, paving the way for the investigation of surface molecular systems beyond the diffraction limit.
Cite
@article{arxiv.2411.18909,
title = {Tip-Enhanced Sum Frequency Generation for Molecular Vibrational Nanospectroscopy},
author = {Atsunori Sakurai and Shota Takahashi and Tatsuto Mochizuki and Toshiki Sugimoto},
journal= {arXiv preprint arXiv:2411.18909},
year = {2025}
}
Comments
The manuscript includes Supporting Information detailing the experimental procedures and data analysis