Ir and Raman spectra of L ‐aspartic acid and isotopic derivatives

The ir and Raman spectra of L ‐aspartic acid, L ‐aspartic‐d 4 acid, and L ‐aspartic‐ 15 N acid as solid samples have been recorded and measured. The data obtained were used to propose a general assignment of the fundamental vibrational modes in the basis of the isotopic shifts measured and correlations with previous data reported for other amino acids and related molecules. A MNDO‐scaled semiempirical force field was obtained, and vibrational frequencies and descriptions were used to support the previous assignments based on experimental features. © 1994 John Wiley & Sons, Inc.