High pressure Raman spectroscopic study of deuterated γ-glycine

Abstract

Raman spectroscopic investigations of deuterated γ-glycine, carried out up to 21 GPa, indicate emergence of a new phase, which is similar to the δ-phase, reported to be formed from the undeuterated γ-glycine at 3 GPa and the transformation to this phase is complete by 6 GPa. Observed pressure -induced variations in CD₂ and N-D stretching modes indicate significant changes in the hydrogen-bonding interactions. Around ~15 GPa, splitting of CD₂ and C-C stretching modes and discontinuous changes in the slope of CO₂ and N-D stretching modes indicate another structural rearrangement across this pressure. The Raman spectra of retrieved phase at ambient conditions suggest that it may be a layered structure similar to the ζ-phase reported to be formed on decompression of the nondeuterated δ-glycine.