POLARIZED RAMAN-SPECTRA AND INTER-MOLECULAR POTENTIAL OF ALPHA-GLYCINE-C-D2 AND DL-ALANINE-ALPHA,BETA-D4 CRYSTALS

Polarized Raman spectra of α‐glycine‐C‐d2 and DL‐alanine‐α,β‐d4 single crystals have been measured. Large factor group splittings due to the non‐bonded atom–atom interaction were observed for the CD2 bending mode of glycine‐C‐d2 and the CD3 asymmetric deformation and the CD3 torsional modes of DL‐alanine‐α,β‐d4. These factor group splittings and their change on N‐deuteration were explained fairly well by a normal coordinate analysis with an intermolecular potential of the exp‐6 type for the non‐bonded atom–atom interaction for the H…H, C…H, C…C and O…H(C) pairs. Good agreement was obtained between the observed and the calculated lattice frequencies on addition of the N…O non‐bonded interaction potential, the hydrogen bond stretching terms and the Coulomb interaction terms to the intermolecular potential. Copyright © 1979 Heyden & Son Ltd.