Study of the Orthorhombic Polymeric Phase of C60Under High Pressure Using Synchrotron X-Ray Powder Diffraction

As an extension of our previously published work (2007) on the orthorhombic phase of polymeric C60, high-resolution powder diffraction experiments under high pressure were recently carried out at the ESRF/SNBL/BM01A beamline. The acquisition times were very short, of the order of 10 minutes. In contrast to our first laboratory experiment, which involved much longer exposures (50–150 hours), no photo-induced transition to a crystalline state of lower symmetry could be observed up to 6 GPa. The obtained powder diffractograms are all consistent with an orthorhombic unit cell. A Birch-Murnaghan equation of state is fitted to the resulting pressure-volume data for the orthorhombic phase.