Reversible Pressure-Induced Amorphization in Solid C70-Raman and Photoluminescence Study

Abstract

We have studied single crystals of C70 by Raman scattering and photoluminescence in the pressure range from 0 to 3 1.1 GPa. The Raman spectrum at 3 1.1 GPa shows only a broadband similar to that of the amorphous carbon without any trace of the Raman lines of CT0. After releasing the pressure from 3 1.1 GPa, the Raman and the photoluminescence spectra of the recovered sample are that of the starting C70 crystal. These results indicate that the C70 molecules are stable up to 3 1.1 GPa and the amorphous carbon high pressure phase is reversible, in sharp contrast to the results on solid Cm. A qualitative explanation is suggested in terms of intermolecular versus intramolecular interactions.