Stability of the crystal structure of L-valine under high pressure

Raman scattering measurements were carried out on a single crystal of L-valine with the pressure increasing from the ambient value to 6.9 GPa. Sudden changes in intensity of the bands were observed in the higher energy spectral range at ∼3 GPa and ∼5.3 GPa. Discontinuities observed in the wave number vs. pressure plots occurred in the complete spectrum at those same pressures, suggesting changes in the crystal structure.