Infrared and Raman spectra ofL-valine nitrate andL-leucine nitrate

A comparative study of the infrared and Raman spectra of L-valine nitrate and L-leucine nitrate helps in determining the role of hydrogen bonds in these crystals. Both compounds have carboxylic and protonated amino groups in the cation while the nitrate ion forms the anion. The wavenumbers of several modes of vibrations were shifted from the expected values in both crystals. The removal of degeneracy of certain modes of vibration of the methyl group suggests that the two methyl groups attached to the same carbon atom are not identical and the symmetry of both of these groups was affected in their respective environments.