EXPERIMENTAL-MEASUREMENT AND AB-INITIO CALCULATION OF RAMAN OPTICAL-ACTIVITY OF L-ALANINE AND ITS DEUTERATED ISOTOPOMERS

Backward scattering in-phase dual circular polarization (DCPI) Raman o ptical activity (ROA) spectra of L-alanine, L-alanine-2d(1), L-alanine -3,3,3-d(3) in H2O and D2O solution in the 800-1700 cm(-1) frequency r egion are presented. Ab initio calculations of normal modes and Raman and ROA intensities have been carried out with a 6-31G basis set and inclusion of a solvent reaction field for stabilization of the zwitter ionic forms. Excellent agreement is found between experiment and calcu lation for both Raman and ROA spectra. However, some discrepancies are noticed between the experimental and theoretical ROA intensities for alanine-2d(1).