RAMAN STUDIES ON C-60 AT HIGH-PRESSURES AND LOW-TEMPERATURES

Vibrational Raman studies on C60 UP to 18.0 GPa and between 4 and 360 K arc presented. No significant changes are observed up to 10 GPa; mode-Gruneisen parameters are calculated. The low pressure, temperature-dependent Raman spectrum shows a sharp shift in peak position and width at 240 K. This is near the point were C60 molecules are reported to begin rotating freely. The data can be explained in terms of rotational-vibrational coupling. Comparison of high pressure and low temperature data suggests the formation of a rotational glass at high pressures.