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Optical Detection of Nuclear Magnetic Resonance with Distant F‐Centre Pairs in KCl
Author(s) -
Jaccard C.,
Ecabert M.
Publication year - 1978
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220870212
Subject(s) - hyperfine structure , excited state , atomic physics , spectral line , polarization (electrochemistry) , hamiltonian (control theory) , chemistry , luminescence , singlet state , nuclear magnetic resonance , physics , optics , quantum mechanics , mathematical optimization , mathematics
In quenched KCl crystals containing more than 10 17 cm −3 F‐centres and excited by unpolarized light in the F‐band at 12 K, the NMR spectra of the neighbouring nuclei are detected at fields between 0.5 and 5 kG and radiofrequencies between 0.1 and 10 MHz as negative changes of the F‐luminescence (1%). This is explained by a non‐radiative disexcitation of F centre pairs through an F + F − state. Its probability is a function of the singlet admixture of the electronic triplet states, which is produced by non diagonal terms of the hyperfine coupling, and depends on the nuclear spin states. It is shown that the optical cycle produces a second order polarization of the nuclei, which is then decreased by applying a resonant rf field. The spin‐Hamiltonian parameters corresponding to the measured NMR spectra are the same as from single F‐centres ENDOR.