J. Phys. I France 6 (1996) 137-147
Radiofrequency and Mössbauer Spectra of a Paramaghetic Ion in the Presence of Hyperfine Interactions and of Tunnel EffectFrançoise Hartmann-Boutron
Laboratoire de Spectrométrie Physique UJF-CNRS, UA 08, Université J. Fourier - Grenoble I, B.P. 87, 38402 Saint Martin d'Hères Cedex, France
(Received 13 July 1995, revised in final form and accepted 2 October 1995)
The influence of a coherent tunnel effect on the magnetic hyperfine structure of a diluted paramagnetic ion, with an electronic ground state , is studied under the assumptions of zero longitudinal magnetic field and slow electronic relaxation. It is shown that the radiofrequency and Mössbauer spectra should be altered, with a change in the number and intensities of the lines. When the tunnelling parameter, , is large compared to the hyperfine structure, the magnetic hyperfine structure splitting should be strongly reduced and it should vanish for . Tunnelling effects have already been observed in EPR experiments on diluted in diamagnetic matrices. The cases of NMR with I=3/2 and of Mössbauer spectroscopy for a transition are considered.
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