Evidence of a structural anomaly at in polymerised
School of Chemistry, Physics and Environmental Science
University of Sussex - Brighton BN1 9QJ, UK
2 European Synchrotron Radiation Facility - F-38043 Grenoble, France
Accepted: 25 May 2000
We report the results of a high-resolution synchrotron X-ray powder diffraction study of polymerised in the temperature range 4 to 40 K. Its crystal structure is monoclinic (space group I2/m), isostructural with . Below 14 K, a spontaneous thermal contraction is observed along both the polymer chain axis, a and the interchain separation along , d1. This structural anomaly could trigger the occurrence of the spin-singlet ground state, observed by NMR at the same temperature.
PACS: 61.48.+c – Fullerenes and fullerene-related materials / 61.10.Nz – Single-crystal and powder diffraction
© EDP Sciences, 2000