Title: NIST Develops Advanced Nonlinear Optical Spectroscopy Technique
NIST researchers have developed a new nonlinear optical spectroscopy technique called Vibrationally-Resonant Sum Frequency Spectroscopy (VR-SFS). This method uses two colors of light – visible and infrared – to probe molecular structures at interfaces with high sensitivity and resolution.
Key features of VR-SFS include:
– Broadband infrared probing of 400-600 cm⁻¹ regions
– Spectral resolution controlled by narrow bandwidth visible light
– Broadband sum frequency light generation
– Multichannel detection for rapid spectral acquisition
– Lateral resolution of 100 μm
The technique measures the second-order nonlinear susceptibility χ(2), which has both resonant molecular vibration components and a non-resonant interface component. The interference between these components allows determination of molecular orientation. For a vibrational mode to be SFG active, it must have both IR (μ) and Raman (α) optical activity.
This new spectroscopy method could enable advanced studies of molecular structures and interfaces in various fields, including materials science, chemistry, and biology.
Source: https://www.nist.gov/laboratories/tools-instruments/nonlinear-optical-spectroscopy
Keywords: spectroscopy, nonlinear, optical, susceptibility, molecular
