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EPR Optical Detection of F Centre Pairs in Alkali Halides I. Pumping Cycle Kinetics and Characteristics of the Resonances
Author(s) -
Ruedin Y.,
Schnegg P.A.,
Jaccard C.,
Aegerter M. A.
Publication year - 1972
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.2220540220
Subject(s) - excited state , alkali metal , chemistry , halide , electron paramagnetic resonance , ground state , spin (aerodynamics) , atomic physics , luminescence , population , quantum tunnelling , resonance (particle physics) , crystal (programming language) , radiative transfer , excitation , electron , analytical chemistry (journal) , nuclear magnetic resonance , physics , condensed matter physics , inorganic chemistry , optics , demography , organic chemistry , quantum mechanics , chromatography , sociology , computer science , thermodynamics , programming language
The electron paramagnetic resonance of F centres in the ground and excited states has been optically detected in the following alkali halide crystals: NaCl, KF, KCl, KBr, KI, RbBr, and RbI. A decrease of the radiative quantum efficiency of the F centre luminescence is observed when microwave transitions are induced between the spin levels. The mechanism responsible for this effect is an electronic tunnelling through the crystal field potential; the electron in the relaxed excited state of an F centre (F̃*) is transfered non radiatively to another nearby F centre in its ground state (F 0 ), and leads to the momentary formation of an α and an F′ centre. Such a process is a function of the total spin of the F̃*‐F 0 pair. The role played by the paired centres is confirmed by measurements at different F centre concentration. Moreover at high optical excitation pumping rate the population of the intermediate complexes (F′‐α) is large enough to allow an estimation of the rate of the reverse process F′ + α → F 0 + F 0 .