This report describes the application of two recently developed spectroscopic techniques surfaceenhanced hyper-Raman and near-JR-excited Fourier transform (FT)-Raman in the structural characterization of biological molecules. Surface-enhanced hyper-Raman scattering (SEHRS) exhibits selection rules that are different from those of normal Raman resonance Raman and JR absorption and it is thus capable of providing new vibrational information unobtainable through existing methodologies. The technique of near-JR-excited FT-Raman almost completely eliminates fluorescence interference and photolytic sample decomposition problems that are frequently encountered in laser Raman studies of biological samples. The recent advent of FT-Raman has thus opened up many exciting opportunities in the vibrational investigation of biological molecules especially those that are highly fluorescent or unstable upon visible laser excitation. Presented as highlights in this report are: (1) a surface hyper-Raman study of an ocular lens chromophore (3- hydroxykynurenine) and copper chlorophyllin (2) an FT-Raman study of three groups of photolabile biomolecules cobalamins bacteriorhodopsin and chiorophylls and (3) near-JR FT-Raman spectra of cytochrome c and model porphyrins.
"Surface-enhanced hyper-Raman and near-IR FT-Raman studies of biomolecules", Proc. SPIE 1403, Laser Applications in Life Sciences, (1 May 1991); doi: 10.1117/12.57329; https://doi.org/10.1117/12.57329