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Assignment of the CH stretching vibrational frequencies in the Raman spectra of lipids
Author(s) -
Faiman Rosalind,
Larsson Kåre
Publication year - 1976
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250040406
Subject(s) - methylene , raman spectroscopy , chemistry , antisymmetric relation , polarization (electrochemistry) , spectral line , molecular vibration , molecular physics , phase (matter) , crystallography , analytical chemistry (journal) , molecule , organic chemistry , optics , physics , astronomy , mathematical physics
A Raman spectroscopic study of several substituted lipids lacking a methyl end group has been carried out in order to assign the vibrational CH stretching modes, all of which arise from the methylene group vibrations. Polarization measurements on the melt and cubic liquid crystalline phase show that the peak in the region of 2885±5 cm −1 is rather weakly polarized in the liquid and liquid crystalline phases, whereas the peak at 2850 cm −1 is rather strongly polarized. Thus it is concluded that the 2850 cm −1 peak arises mainly from the methylene symmetric stretching modes and the 2885±5 cm −1 peak arises mainly from the methylene antisymmetric stretching modes. The band at about 2930 cm −1 is assigned to a symmetric methylene stretching vibration. The implications in the interpretation of chain mobility and chain conformation are discussed.