Raman spectroscopic study of DL valine under pressure up to 20 GPa

• dl-valine crystals were grown by slow evaporation methods.
• Raman spectra of dl-valine.
• Structural phase transitions under pressure.
• Modifications on hydrogen bonds.

dl-valine crystal was studied by Raman spectroscopy under hydrostatic pressure using a diamond anvil cell from ambient pressure up to 19.4 GPa in the spectral range from 40 to 3300 cm−1. Modifications in the spectra furnished evidence of the occurrence of two structural phase transitions undergone by this racemic amino acid crystal. The classification of the vibrational modes, the behavior of their wavenumber as a function of the pressure and the reversibility of the phase transitions are discussed.

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