PHONON-SPECTRA OF METASTABLE C60 SYSTEMS OBTAINED UNDER HIGH-ENERGY IMPACTS

Low-frequency infrared (IR) spectra of fullerene and metastable forms of C60 obtained at high pressures and temperatures have been investiga ted along with the spectra of natural diamond and graphite in the rang e from 8 to 170 cm(-1). Several bands of C60 and the diamond-like phas e exist in the reflection IR spectra of the low-temperature phase at c omparatively low pressures. In the new solid phase, most bands shift w ith an increase in pressure. The bands corresponding to the diamond-li ke structures with sp(3) hybridization were only observed in the high- pressure high-temperature phase. These low-frequency modes can be pres umably attributed to zone- and space-folded phonons. (C) 1998 American Institute of Physics.