High pressure Raman spectra of d-threonine crystal

Raman spectra of d-threonine crystal were recorded for pressures up to 8.5 GPa. Modifications in the lattice modes indicate that the crystal undergoes two structural phase transitions, the first in the 1.9–2.4 GPa pressure range and the second in the 5.1–6.0 GPa pressure range. Splitting of modes and changes in the intensity of several bands suggest a conformational reorientation of the molecule in the crystal framework between 3.5 and 4.3 GPa. We discussed ours results by comparing with previous high-pressure investigation on l-conformer.