Methyl group tunnelling and coupling to internal vibrations
- 28 July 1978
- journal article
- Published by IOP Publishing in Journal of Physics C: Solid State Physics
- Vol. 11 (14), 3039-3047
- https://doi.org/10.1088/0022-3719/11/14/024
Abstract
A coupling between the librations and internal vibrations is suggested to decrease the librational tunnelling frequency nu t of the methyl group at low temperatures. The coupling originates from a low symmetry of the lattice potential at the site of the group. The experimentally observed nu t at liquid helium temperatures is shown to be related to the ground and excited librational states. The initial temperature dependence of the coupling is determined by the methyl group distortion. A distortion becoming smaller when the temperature is raised is shown to make nu t larger.Keywords
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