Classical Raman spectroscopy

The application of classical Raman spectroscopy, using the mercury radiation at A 253.6 nm as the excitation source, permitted recording20 of more than 20 peaks for sucrose below 500 cm-1. The observed frequencies below 100 cm"1 were interpreted as due to inter-ring oscillations, which was also the conclusion reached from a far-infrared study84 of glucose and sucrose. 

Classically, Raman spectroscopy arises from an induced dipole in a molecule resulting from the interaction of an electromagnetic field with a vibrating molecule. In electromagnetic theory, an induced dipole is a first-rank tensor formed from the dot product of the molecular polarizability and the oscillating electric field of the photon, (jl = a-E. Assuming a harmonic potential for the molecular vibration, and that the polarizability does not deviate significantly from its equilibrium value (a0) as a result of the vibration... 

Since Chapman and coworkers (Chapman et al., 1966) first attempted to investigate the membrane structure by vibrational spectroscopy, there has been considerable technical improvement. Infrared and Raman spectroscopy are now routine tools for structural investigations in membranes (Fringeli and Gunthard, 1981 for ATR-IR Casal and Mantsch, 1984 and Mendelsohn and Mantsch, 1986 for FTIR Verma and Wallach, 1983 Levin, 1984 for classical Raman spectroscopy and Levin and Neil Lewis, 1990 for FT-Raman spectroscopy). 

Applications of non-classical Raman spectroscopy resonance Raman, surface enhanced Raman, and nonlinear coherent Raman spectroscopy ... 

Near-infrared excited FT-Raman spectroscopy has recently begun to show promise (Schrader, 1990), because the fluorescence is drastically reduced. It has the Jaquinot advantage over classical Raman spectroscopy, which affords a better signal-to-noise ratio. FT-Raman is an excellent technique to supplement FTIR difference spectroscopy in investigations of intramolecular protein reactions because Raman spectra have the... 

Pioneering work by the Alix laboratory on the secondary structure of human elastin and the solubilized K-elastin, estimated the molecule to be composed of 10% a-helices, 35% P-strands and 55% undefined conformation. These estimations were based on Fourier transform infrared (FTIR), near infrared Fourier transform Raman spectroscopy and circular dichroism (CD) (15). To further investigate the nature of the elasticity, polypeptides of hydrophobic sequences containing exons 3, 7, and 30 of human elastin were analyzed by CD and Classic Raman spectroscopy, revealing polyproline II (PPII) helix secondary structures in both the aqueous and solid phase. Further analysis of exon 30 by FTIR spectroscopy determined that this sequence was characterized by both PPII as well as p-sheets structures (15). The presence of these structures were dependent on temperature, concentration and / or time, where lower temperatures and concentrations favored the PPII structure and higher temperatures and concentrations favored p-sheets (16). 

Polymer applications in Raman spectroscopy were reviewed [375,407,408], as well as general applications in the chemical industry [52,384,409]. For Raman spectroscopy of synthetic polymers, cfr. ref. [394], The use of Raman spectroscopy in art analysis has recently been reviewed [410,410a]. For applications of non-classical Raman spectroscopy, cfr. ref. [411] and for FT-Raman spectroscopy, cfr. also ref. [412]. A textbook is available [394]. 

Kiefer W (1995) Applications of non-classical Raman spectroscopy resonance Raman, surface enhanced Raman, and nonlinear coherent Raman spectroscopy. In Schrader B (ed.) Infrared and Raman Spectroscopy, pp 465-517. Weinheim VCH Verlag. 

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