Reorientational dynamics of solid C70 probed by positive muons

Roderick M. Macrae, Kosmas Prassides, Ian M. Thomas, Emil Roduner, Christof Niedermayer, Ulrich Binninger, Christian Bernhard, Anselm Hofer, Ivan D. Reid

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

The dynamics of muonium (Mu) adducts to C70 in the crystalline state have been studied using zero-field muon spin relaxation (ZF-μSR) and avoided level crossing muon spin resonance (ALC-μSR) spectroscopy. The two techniques are sensitive to complementary ranges of temperature and together give a complete and consistent picture of the molecular motion. The behavior of the MuC70 radicals which are characterized by a prolate hyperfine matrix with components Dxx = -6.8(2) MHz, Dyy = -3.7(2) MHz, Dzz = 10.5(2) MHz is well-described by a pseudostatic model with a temperature-dependent order parameter. In contrast, MuC60 shows a spherically isotropic diffusive or jump reorientation mechanism. C70 is frozen on a time scale of around 30 ns up to 170 K. On further heating, the motion is found to be complex, consisting of a uniaxial rotation part together with a nutational or jumping motion of the unique axis. Anisotropy on the 30 ns time scale persists up to 370 K, well into the face-centered cubic phase of solid C70. Above 390 K, the reorientational motion is essentially isotropic and the avoided level crossing resonance line disappears.

Original languageEnglish
Pages (from-to)12133-12141
Number of pages9
JournalJournal of Physical Chemistry®
Volume98
Issue number47
DOIs
Publication statusPublished - 1994 Jan 1
Externally publishedYes

ASJC Scopus subject areas

  • Engineering(all)
  • Physical and Theoretical Chemistry

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