Neutron spectroscopy of fullerite hydrogenated under high pressure; evidence for interstitial molecular hydrogen

Abstract

Inelastic neutron scattering spectra of a hydrofullerite quenched after synthesis at 620 K under a hydrogen pressure of 0.6 GPa, and of the same sample after annealing at 300 K for 35 h, which reduced the hydrogen content by molecules per unit, were measured at 85 K. The quenched sample is shown to consist of molecules with and of interstitial molecular hydrogen. The interstitial molecular hydrogen left the sample during annealing at room temperature, whereas the molecules were stable at this temperature. The intramolecular and intermolecular vibrations of and in the fullerite are discussed in view of the measured spectra.