Destruction mechanism of color centers and recombination luminescence in NaCl-Cd crystal phosphors

The authors have studied the origin of integral thermoluminescence peaks and the destruction mechanism of color centers during thermal relaxation of X-irradiated NaCl-Cd phosphors. The luminescence spectra have also been studied, and previous similar results are discussed.     

The mechanism of disintegration of color centers and the non-stationary recombination luminescence of NaCl-Ag phosphor crystal. I

A combined method has been used to study the disintegration processes of the 355, 465, and 720 color centers of NaCl-Ag phosphor in the temperature range 100–550 ° K. The emission spectra of thermostimulated and photostimulated recombination luminescence of NaCl-Ag excited by X-rays at various temperatures were also studied. The possibility of ion-electron and ion-hole disintegration mechanisms of the color centers in the phosphor crystal at low temperatures is examined.The authors thank Doctor of Physical and Mathematical Sciences Ch. B. Lushchik for discussion of the subjects touched upon in the present paper, and also Yu. N. Evstifeev for assistance in performing the experiment.     

Investigation of the disintegration mechanism of color centers,and recombination luminescence of the (NaCl-Ag,Ca)-crystal phosphor. II

The investigation of relaxation processes in alkali-halide phosphor crystals excited by X-rays is continued.The mechanism of disintegration of color centers, the occurrence of thermoluminescence peaks, as well as the spectra of thermally stimulated and photo-stimulated luminescence, are investigated for a (NaCl-Ag, Ca)-crystal phosphor.     

The interaction of photoexcited color F-centers with microdefects in the crystal lattice of alkali-halide crystal phosphors. II

The interaction of different microdefects with excited and nonexcited F-centers was studied, using the methods of thermal decolorization, thermal luminescence, photothermal decolorization and photothermal luminescence.A comparison of experimental data with the results of theoretical calculations of the corresponding curves enables an estimate to be made of certain kinetic characteristics of the processes in questions.     

Effect of microdefects in crystal lattice on certain luminescence relaxation processes in alkali halide phosphor crystals

A further development of ideas on an ionic mechanism for the activation of certain relaxation processes in recombination luminescence of alkali halide phosphor crystals is presented. It is shown that each stage of the thermal discoloration process in the phosphor crystals corresponds to disruption of the F-band in an isolated microsection of the specimen. The effect of the degree of plastic deformation on the relative proportions of F-center concentrations on various microregions of the crystal was investigated. The effect of impurity ions, of their concentration, arid of the crystal plastic deformation on the photothermal stability of the F-centers and on the thermal quenching of luminescence during photoexcitation of activator color centers in NaCl-Ag phosphor crystals was also studied.     

Microscopic investigation of the creation and destruction of color centers in alkali-halide crystals

A new microscopic method for the study of color-center creation in alkali-halide single crystals is proposed. The creation and destruction of F- and M-color centers in NaCl single crystals and also in threadlike NaCl crystals have been studied on topographically different microareas of the samples.The authors are deeply indebted to Dr. Ch. B. Lushchik, M.A. Elango, and K. I. Gindina for valuable discussions of the problems encountered and also for providing a number of crystals for the investigation.     

Influence of the degree of plastic deformation on the thermal photostability of F-centers in NaCl crystals

The effect of plastic deformations on the thermal stability and thermal photostability of F-centers in NaCl crystals was examined. The thermal photostability of F-centers and the thermal stability of some of these centers increases in proportion to the degree of plastic deformation. The concentration of the less stable F-centers increases due to plastic deformation. The effect was studied in crystals which were deformed before and after x-ray excitation. The results were interpreted from the viewpoint of an ionic activation mechanism in the thermal and photothermal decomposition of the color centers in alkalihalide crystals.The authors are indebted to Yu. L. Lukantsever for an evaluation of the results of this work.     

Functor of weakly additive τ-smooth functionals and mappings

We present a criterion for the τ-smoothness of weakly additive order-preserving functionals and establish that the functor of τ-smooth weakly additive functionals preserves the perfectness of mappings. We prove that if a continuous mapping between Tikhonov spaces is such that the mapping between the corresponding spaces of weakly additive functionals generated by it is open, then the indicated mapping is also open. It is shown that the converse statement is true under certain additional conditions.     

Some categorical properties of the functors O τ and O R of weakly additive functionals

In the paper, the spaces of weakly additive τ-smooth and Radon functionals are investigated. It is proved that the functors of weakly additive τ-smooth and Radon functionals weakly preserve the density of Tychonoff spaces, and the functor of weakly additive τ-smooth functionals forms a monad in the category of Tychonoff spaces and their continuous mappings. Examples and remarks are given showing that these functors fail to satisfy certain Shchepin normality conditions. Problems having positive solutions for normal functors are presented.     

Homotopy Properties of the Space If(X) of Idempotent Probability Measures

A subspace I_f(X) of the space of idempotent probability measures on a given compact space X is constructed. It is proved that if the initial compact space X is contractible, then I_f(X) is a contractible compact space as well. It is shown that the shapes of the compact spaces X and I_f(X) are equal. It is also proved that, given a compact space X, the compact space I_f(X) is an absolute neighborhood retract if and only if so is X.