A pair correlation function study of the structure of C60

A. K. Soper, W. I.F. David, D. S. Sivia, T. J.S. Dennis, J. P. Hare, K. Prassides

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35 Citations (Scopus)

Abstract

The inter- and intra-molecular structures of C60 have been studied at 20 K and 295 K by means of the pair correlation function using low-angle pulsed neutron diffraction. Two methods of inversion of the structure factor data are presented. Direct inversion of the data using a Monte Carlo algorithm yields a model-independent combined intra- and inter-molecular pair correlation function. This clearly indicates, even at 295 K, the presence of two distinct C-C bond lengths of 1.377(15) AA and 1.458(6) AA. Further analysis was performed using a truncated icosahedral model for the intra-molecular behaviour in combination with a free-form Monte Carlo solution for the inter-molecular pair correlation function. This analysis confirms two distinct nearest-neighbour C-C bond lengths but indicates that the difference has a precision of order 0.005 AA. The optimal values at both 20 K and 295 K obtained from this analysis are 1.400 AA and 1.440 AA implying that the molecular structure is essentially unchanged between these two temperatures. There are, however, distinct differences between inter-molecular bonding at 20 K and 295 K that are consistent with an orientational ordering transition at 260 K. In particular, the room temperature data can be accurately modelled in terms of a face-centred-cubic structure in which the C60 molecules adopt a completely random orientation with respect to one another.

Original languageEnglish
Article number009
Pages (from-to)6087-6094
Number of pages8
JournalJournal of Physics: Condensed Matter
Volume4
Issue number28
DOIs
Publication statusPublished - 1992

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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