Methine stretching vibrational frequencies

L-Alanine, the simplest chiral amino acid, has been the subject of the most extensive study and serves as the prototype for the other amino acids. A complete vibrational assigrunent has been obtained (85, 86) based on solution phase IR and Raman spectra and solid phase Raman spectra for alanine-do, alanine-C -di, alanine-C(3-d3, and alanine-C -d-C -d3. In the CH stretching region, the antisymmetric methyl stretches are assigned at 3006 and 2989 cm , the methine stretch at 2970 cm , and the Fermi resonance diad involving the symmetric methyl stretch and the overtone of the antisymmetric methyl deformation at 2950 and 2893 cm. The calculated frequency for the unperturbed symmetric methyl stretch is 2930 cm . 

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