RAMAN-SCATTERING STUDY OF BENZOPHENONE UNDER HIGH-PRESSURE

Benzophenone (C6H5COC6H5, BPH) has been studied by high pressure Raman spectroscopy up to 100 kbar using a diamond-anvil cell at room temper ature. The splittings of several non-degenerate internal modes at high pressure are interpreted as the dimerization of BPH molecules. The di sappearance of all external and most internal lines found at pressures above 100 kbar is explained as a crystalline-to-amorphous phase trans formation. A mechanism of pressure-induced amorphization driven by ran domly-oriented dimers of BPH molecules is proposed. Upon release sf pr essure, the virgin crystalline state is recovered, but with substantia l hysteresis.