Infrared absorption spectra of δ-AlOOH and its deuteride at high pressure and implication to pressure response of the hydrogen bonds

Abstract

Infrared absorption spectra of δ-AlOOH and its deuterated form (δ-AlOOD) were measured at high pressure using a diamond anvil cell under a quasi-hydrostatic pressure condition using helium as a pressure-transmitting medium. Two absorption bands at 1180 cm−1and 1330 cm−1 involving vibrations of hydrogen and oxygen atoms shifted to higher frequencies with increasing pressure up to 10 and 12 GPa for δ-AlOOH and δ-AlOOD, respectively. In contrast, at higher pressures the two bands did not shift so much. The pressure-response on the infrared spectra has a close relationship to the symmetrization of the hydrogen bonds and change in the compressibility which was observed from X-ray diffraction measurements.