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On the luminescence and absence of luminescence of F centers

Bartram, RH; Stoneham, AM; (1975) On the luminescence and absence of luminescence of F centers. Solid State Communications , 17 (12) 1593 - 1598. 10.1016/0038-1098(75)91003-0. Green open access

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Abstract

A model, proposed originally by Dexter, Klick and Russell, is used to explain the occurence or non-occurence of F-center luminescence in ionic crystals, in terms of a simple two-state configuration coordinate diagram. In this model, which works for all known cases, luminescence is quenched by a competing non-radiative process whenever the intersection of the ground and excited state curves lies below the energy reached in absorption in a vertical (Franck-Condon) transition. The criterion for the occurence of luminescence is expressed as Λ < 1/4 , where Λ (=excited-state lattice-relaxation energy/optical-absorption energy) is a parameter, related to the relative displacement of the two curves, which can be inferred from data on the temperature dependence of the F-band line width. Thus the possibility of observing luminescence can be predicted from optical absorption data alone. It is found emperically that Λ for alkali halides with rocksalt structure is independent of lattice parameter, and the observed dependence of Λ on the ratio of ionic radii in terms of ion-size effects. Values of Λ range from 0.009 for CsF to 0.831 for LiI; NaCl with Λ = 0.260 is a marginal case for luminescence.

Type: Article
Title: On the luminescence and absence of luminescence of F centers
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/0038-1098(75)91003-0
Publisher version: http://dx.doi.org/10.1016/0038-1098(75)91003-0
Language: English
Additional information: Text made available to UCL Discovery by kind permission of Elsevier, 2012
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/59741
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