SINGLE-CRYSTAL X-RAY DIFFUSE-SCATTERING STUDIES OF THE INTERMOLECULARINTERACTIONS IN SOLID C-60

Current microscopic models of the C-60 intermolecular interactions fai l to give an accurate description of the ordering phenomena in solid C -60, where orientational correlations of the fullerene molecules play a leading role, At room temperature these orientational correlations p roduce x-ray diffuse scattering intensity modulations whose analysis i s a good test for the microscopic models. Below the 259K transition, t he remaining x-ray diffuse scattering was measured up to large wave ve ctor values. Its analysis confirms that the low-temperature structure is characterised by two nearly degenerate and randomly distributed ori entations of the C-60 molecules.