High-pressure Raman spectra of L-histidine hydrochloride monohydrate
crystal
VIBRATIONAL SPECTROSCOPY, 57 (1):
102-107 (2011)DOI: 10.1016/j.vibspec.2011.05.010
Zusammenfassung
Single-crystals of L-histidine hydrochloride monohydrate, C6H9N3O2
center dot HCl center dot H2O, were studied by Raman spectroscopy as a
function of pressure in a diamond anvil cell up to 7.5 GPa at room
temperature over the spectral range 3450-30 cm(-1). The effect of
changing pressure on the vibrational spectrum is discussed. From the
analysis of results we inferred that the crystal undergoes a reversible
structural phase transition between 2.7 and 3.1 GPa. This transition is
characterized by the splitting of a band related to torsion of CO2-, the
disappearance and appearance of modes related with stretching of OH- and
deformation of CO2-, as well as with bands of low wavenumber which are
assigned as lattice modes, and by the discontinuities of the curves of
wavenumber versus pressure. Pressure coefficients for all modes observed
in this work are also given. (C) 2011 Elsevier B.V. All rights reserved.