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The JT effect in an isolated fullerene ions causes an instantaneous distortion
to a lower symmetry (either D3d or D5d for anions;
for cations, distortions of D2h or C2h symmetry
are also possible). However, as there are multiple distorted configurations
with the same energy, quantum-mechanical tunnelling, or pseudorotation
(rotation of a distortion), between these configurations means that the
overall symmetry will still be icosahedral, and the JT effect is said
to be dynamic. It is therefore only possible to observe a distortion in
an isolated ion if measurements can be made on a sufficiently fast timescale;
this is believed to be the order of femtoseconds.
Two EPSRC-funded projects (2002-2007) in collaboration with Profs Steve
Meech and David Andrews at the University of East Anglia aimed to probe
this pseudorotation. The Norwich team made experimental measurements of
the pseudorotation whilst the Nottingham team carried out theoretical
calculations.
The figures below show how the probability of finding the system in different
distorted configurations (labelled a, b and c) could
vary as a function of time (see ref 4 below for full details).
Publications
- Hope M. J., Higlett M. P., Andrews D. L, Meech S. R., Hands I. D.,
Dunn J. L. and Bates C. A., Observation of ultrafast internal conversion
in fullerene anions in solution, Chemical Physics Letters 474,
112–114 (2009). doi:10.1016/j.cplett.2009.04.066
- Hands I.D., Dunn J.L., Bates C.A., Hope M.J., Meech S.R. and Andrews
D.L., Vibronic interactions in the visible and near-infrared spectra
of C60- anions. Physical Review B 77,
115445 (2008).doi:
10.1103/PhysRevB.77.115445
- Dunn J.L., Hands I.D., Bates C.A., Pseudorotation in fullerene
anions, Journal of Molecular Structure 838, 60-65 (2007).
- Hands I. D., Dunn J. L. and Bates C. A., Theoretical calculation
of pseudorotation rates applicable to the C60-
ion, Physical Review B 73, 235425 (2006). doi:
10.1103/PhysRevB.73.235425
- Hands I. D., Sindi L. M., Dunn J. L. and Bates C. A., Theoretical
treatment of pseudorotation in the Jahn-Teller C60+
ion, Physical Review B 74, 115410 (2006). doi:
10.1103/PhysRevB.74.115410
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