US-UK Cooperative Research: Studies of Thermoluminescence and Catholuminescence

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This award will support collaborative research between Dr. S. W. McKeever, Oklahoma State University and Dr. P. D. Townsend, University of Sussex, England. Dr. McKeever will spend six months in Dr. Townsend's laboratory, working on three distinct projects: 1) conductivity and cathodoluminescence of II-VI semiconductors, 2) absorption and luminescence of doped lithium fluoride and 3) the thermoluminescence (TL) of quartz. During this period, Dr. McKeever will make extensive use of apparatus for the recording of 3D TL glow-curves and of cathodoluminescence. The 3D TL facilities in particular are unique and not available at Dr. McKeever's home institution. The materials which will be studied are cadmium telluride, lithium fluoride and silicon dioxide. Each of these materials has significant technological importance. In the CdTe work, the investigators will examine edge emission during low temperature cathodoluminescence in order to study bound exciton relaxation luminescence. The purpose is to characterize the excitonic states in different samples and to use this information in the study of the non-linear optical properties of the material. The '3D' TL apparatus will be used for the lithium fluoride studies. The lithium fluoride samples are variously doped with copper, magnesium, and phosphorus impurities. The investigators will look for evidence of perturbations in the emission due to impurity clustering effects within the lattice. These properties are to be used in assessing the optimal impurity concentrations and method of production of lithium fluoride: copper, magnesium, and titanium for dosimetry applications. The silicon dioxide work will involve cathodoluminescence and 3D TL measurements to examine the effects on the luminescence properties of various thermal, radiation and electrolitic sweeping treatments in order to more clearly understand the TL behavior of this material. Dr. McKeever is internationally well known in the field of thermoluminescence and its application in dosimetry and in dating of natural sediments.