[Press Release] Pioneering second-order nonlinear vibrational nanoscopy for interfacial molecular systems beyond the diffraction limit
The schematic illustration of tip-enhanced SFG (TE-SFG) measurements of an inhomogeneous surface molecular system beyond the diffraction limit (Credit: American Chemical Society, Restriction: News organizations may use or redistribute this image, with proper attribution, as part of news coverage of this paper only.)
Release Summary
Sum-frequency generation (SFG) is a powerful vibrational spectroscopy that can selectively probe molecular structures at surfaces and interfaces, but its spatial resolution has been limited to the micrometer scale by the diffraction limit of light. Here, we overcame this limitation by utilizing a highly confined near field within a plasmonic nanogap and successfully extended the SFG spectroscopy into nanoscopic regime with ~10-nm spatial resolution. We also established a comprehensive theoretical framework that accurately describes the microscopic mechanisms of this near-field SFG process. These experimental and theoretical achievements collectively represent a groundbreaking advancement in near-field second-order nonlinear nanospectroscopy, enabling direct access to correlated chemical and topographic information of interfacial molecular systems at the nanoscale.
