Abstract
Raman spectroscopy investigations of DL-alanine crystal under high
pressures have been carried out up to 18.0 GPa. For instance, around 1.0
GPa and between 1.7 and 2.3 GPa changes in the Raman profile were
observed and associated to conformational changes of the molecules in
the unit cell or to a phase transition accompanied to slight
conformational change of the molecule through CH and CH3 groups.
Moreover, between 6.0 and 7.3 GPa, the appearance of a new low energy
lattice modes and to the splitting of a band assigned to the stretching
vibration of the CCH3 moiety were related to a second phase transition.
Finally, changes in lattice modes, red shift of the band associated to
CCH3 stretching and increasing of line-width of the band associated to
the wagging of CO2, between 11.6 and 13.2 GPa, are ascribed to a third
phase transition. On release of pressure the original phase was obtained
again. (C) 2010 Elsevier B.V. All rights reserved.
Users
Please
log in to take part in the discussion (add own reviews or comments).