Espalhamento Raman em policristais de L-prolina sob altas pressões hidrostáticas

Abstract

In this work, we have presented a Raman scattering study of L-proline (C5H9NO2) crystals at room temperature and high hydrostatic pressure conditions over the spectral range 30−3200 cm−1. We have proposed an assignment of the Raman bands to various vibration modes based on previous Raman spectroscopy studies of L-proline and others amino acids such as L-leucine, L-isoleucine and L-valine. The high-pressure Raman espectra suggest that the L-proline crystal undergoes a reversible structural phase transition between 1.5 and 2.5 GPa, associated with conformational changes of L-proline molecules in the unit cell. It also was observed at about 5.2 GPa a conformational change that may be related with modifications of the proline pyrrolidine ring.