High-pressure Raman investigations of phase transformations in pentaerythritol(C(CH2OH)4)

Abstract

Our high-pressure Raman scattering experiments on pentaerythritol (C(CH2OH)4)show that this compound undergoes at least three phase transformations up to 25GPa. Splitting of various modes at ∼6.3, ∼8.2 and 10 GPa suggests that thesephase transformations result in lowering of crystalline symmetry. A verysmall discontinuous change in slope of most of the Raman-active modes isobserved at 0.3 GPa. However, no other signature of a phase transition wasobserved at this pressure. The observed correlation of the pressures for theonset of the two phase transformations with the limiting values of thedistances between various non-bonded atoms in the parent phase suggeststhat the molecular rearrangements across the phase transformations arenot very drastic. In addition, our earlier Fourier transform infrared andpresent Raman investigations indicate that high-pressure compression leadsto increase in strength of the hydrogen bond present in this compound.