This title appears in the Scientific Report : 2003 

Methyl rotational potentials of trimethyl metal compounds studied by inelastic and quasielastic neutron scattering
Prager, M.
Grimm, H. / Desmedt, A. V. / Lechner, R. E.
Neutronenstreuung; IFF-NST
Chemical physics, 292 (2003) S. 161 - 169
Amsterdam [u.a.] Elsevier Science 2003
161 - 169
Journal Article
Kondensierte Materie
Chemical Physics 292
Please use the identifier: in citations.
Neutron scattering data on classical and quantum rotation of methyl groups in the organometallic molecular crystal In(CH3)(3) are presented. The tunneling spectra are analyzed using the mean field single particle model of rotational tunneling. The presence of six inequivalent rotors of equal occurrence probabilities in In(CH3)(3) is reflected in the number and intensities of the transitions. In a similar way classical spectra are interpreted as superposition of quasielastic Lorentzians. A consistent combination of tunneling and quasielastic spectroscopies is based on equal relative intensities of the respective spectral components and allows a determination of the coefficients of a Fourier expansion of the rotational potentials up to second order with only a few percent of uncertainty. The results are compared to published data on the homologues Al and Ga compounds on the basis of the molecular and crystal structures. Intra-and intermolecular interactions are found to be of similar importance. (C) 2003 Elsevier Science B.V. All rights reserved.