Low Temperature Physics: 32, 1020 (2006); https://doi.org/10.1063/1.2389008 (8 pages)
Физика Низких Температур: Том 32, Выпуск 11 (Ноябрь 2006), c. 1345-1354    ( к оглавлению , назад )

The physics of rotational tunneling: hole-burning spectroscopy of methyl groups

Mark M. Somoza and Josef Friedrich

Physik-Department E14 and Lehrstuhl für Physik Weihenstephan Technische Universität München, Freising, 85350 Germany
E-mail: J.Friedrich@lrz.tu-muenchen.de

Received February 13, 2006, revised May 29, 2006.

Аннотация

Methyl groups are most outstanding quantum systems due to their inherent symmetry properties which cannot be destroyed by any kind of lattice disorder. We show how optical hole-burning techniques can be employed to measure rotational tunneling relaxation processes. Since the tunneling parameters are extremely sensitive to changes in the host lattice, there is a rich variety of relaxation phenomena that can be observed. Hole-burning techniques have the capability of measuring not only extremely slow processes with high precision but also rather fast processes. We exploit this possibility to show that the relaxation times at 2 K change by 14 orders of magnitude if the permutation symmetry of the methyl group is destroyed by asymmetric deuterium substitution.

PACS:
33.15.Hp - Barrier heights (internal rotation, inversion, rotational isomerism, conformational dynamics)
42.50.Ct - Quantum description of interaction of light and matter; related experiments
42.62.Fi - Laser spectroscopy
78.55.Kz - Solid organic materials

Ключевые слова: rotational tunneling relaxation, nuclear spin polarization, symmetry species conversion, substitution of hydrogen by deuterium in the methyl group.