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On F‐ and F H ‐centres in cesium halides
Author(s) -
Vandekhaeghe A.,
Jacobs G.
Publication year - 1977
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.2220830213
Subject(s) - excited state , caesium , atomic physics , luminescence , chemistry , ion , conduction band , ground state , halogen , absorption (acoustics) , halide , physics , optics , electron , inorganic chemistry , organic chemistry , quantum mechanics , alkyl
Fg‐centres are formed in CsI doped with foreign halogen ions, by irradiation in the F‐band at 180 K. They are observed in CsI:Br − , CsI:Cl − , and CsI:F − . The lifetime of the relaxed excited state of the F‐centre in pure CsI and of the F H ‐centre is determined by measuring the repopulation of the ground state after depletion with laser light. The results are τ R = 3 μs for the F‐centre in CsI, 360 ns for CsI: Br − , 400 ns for CsI: Cl − , 290 ns for CsI: F − . The luminescence decay time of the F‐centre in CsCl is found to be 2 μs, the relaxed excited state lying 0.07 eV under the conduction band. The results on the F H ‐centre suggest that the lowest emitting level is 2s with a large admixture of 2p character. Simultaneously with the formation of F H ‐centres, new absorption bands appear in the M‐band region, possibly due to M H ‐centres.