Far-infrared spectra of solid methanol at high pressures

Far-infrared spectra of methanol samples in diamond anvil cells at ambient temperature and at pressures up to 11 GPa are reported. The liquid forms a metastable glass at about 3.6 GPa, the absorption spectrum of which consists of a single broad band which shifts to higher wavenumbers with increase of pressure. On maintaining the pressure at a high value, the glass usually transforms to a crystal and at least five distinct peaks are then observed. The evolution of these peak wavenumbers with pressure indicates that no further transitions occur. An increase in hydrogen bond strength by a factor of about 1.5 is deduced for the crystal over the pressure range 3.6 to 11 GPa.