BAND SHAPE OF THE $CH_{1}$ STRETCHING BANDS - SOLID POLYETHYLENE.
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Date
1991
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Ohio State University
Abstract
The infrared spectra of large molecules of biological interest such as proteins and lipids, show large structureless bands. To separate the components in the massive absorptions, it is necessary to know the band shapes and bandwidths of the functional groups involved in the absorption. We present here the case of the $CH_{2}$ stretching bands. We used solid polyethylene obtained from an 0-xylene solution as a model system for the $CH_{2}$ groups. The spectra at several thickness were obtained. Four bands were visually observed in the 2900 $cm^{-1}$ region. After Fourier deconvolution and band fitting, eight bands were retrieved: four for the CH stretch bands and four for the combination bands. The bandwidths are 13.3 and $6.9 cm^{-1}$ for the anti- and symmetric $CH_{2}$ stretch band, respectively. The band shape ratio (Cauchy index over the sum of Cauchy and Gauss indices) is near 0.71 for the two cases. The method used to retrieve these values as well as the assignment of the bands will be presented.
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Author Institution: D\'{e}partement de chimie-biologie, Universit\'{e} du Qu\'{e}bec \hat{a} Trois-Rivi\'{e}res