High‐pressure variable temperature Raman studies on hexamethyl benzene crystals

The Raman spectra of hexamethyl benzene and HMB‐d18 have been recorded as a function of temperature between 4 K and 400 K and as a function of pressure up to 8kbar. In the low‐frequency region, librational and torsional modes have been distinguished. The spectra indicate a phase transition to a high‐pressure phase IV. The polarized infrared spectra of single crystals have also been observed at different temperatures.