Raman spectroscopic study of orthorhombic l-cysteine under pressure up to 20.2 GPa

Abstract To investigate the amino acids structure properties under high pressure, orthorhombic l -cysteine crystals were studied by Raman spectra in the spectral range from 50 to 3200 cm −1 . And the pressure range of this work has been extended from 6.5 to 20.2 GPa. The results show that two structural phase transitions are discovered, which are in the range of 1.8–3.6 GPa, 6.9–7.8 GPa, respectively. The vibrational modes classification, the relationship of their wavenumber as a function of the pressure and the reversibility of the phase transitions are discussed.