高圧ラマン散乱で見た水素結合の局所対称性 Local Symmetry of Hydrogen-Bond Investigated By High-Pressure Raman Spectroscopy
High pressure Raman scattering measurements are performed on hydrogen-bonded molecular system, crystal of squaric acid H<SUB>2</SUB>C<SUB>4</SUB>O<SUB>4</SUB>. Specific intramolecular vibrational modes of squaric dianion C<SUB>4</SUB>O<SUB>4</SUB><SUP>2-</SUP> are found to disappear under pressures due to vanishment of the molecular distortion. This indicates that application of presure deformed the proton potential from double-minimum to single-minimum type. We fourther found a novel quantum paraelectric state, where deformed dianions can not show any ordering down to the lowest temperature, in the pressure range of 3.0-4.5 GPa.
日本結晶学会誌 40(1), 43-47, 1998-02-28
The Crystallographic Society of Japan