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.     

Kinetics of recombination interaction of impurity centers in crystal phosphors

Various nonlinear regimes of stationary emission of crystal phosphors with several types of impurity centers are investigated. In the case of two types of centers (radiative and nonradiative recombination), general equations are derived which connect the emission yield with the volume density of the excitation, given the temperature and the parameters of these centers. The degree of nonlinearity K and the temperature sensitivity R_T are obtained for various ratios of the parameters of the centers and for definite ranges of excitation conditions. The conditions needed to obtain anomalously high values of K and R T are established, and their limiting values upon saturation of the effective nonradiative-recombination centers are estimated. The diverse roles of the quenching processes in practical applications of crystal phosphors is discussed.Translated from Trudy Ordena Lenina Fizicheskogo Instituta im. P. N. Lebedeva, Vol. 117, pp. 3–54 (1980).     

Photostimulated luminescence and its capabilities in studies of recombination in phosphors

An analysis is made of the effects of various factors on the temperature dependence of the brightness of photostimulated luminescence. A detailed study is made of the thermal dissociation of hole centers, the thermal ionization of one type of electron center, and repeated localization of electrons. It is shown that the brightness changes observed in photostimulated luminescence as a sample is heated reflect not only the mechanism of photostimulated electron liberation, but also several fundamental processes governing the mechanism for the thermal deexcitation of phosphors.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 2, pp. 50–56, February, 1971.     

The decay kinetics of radical-recombination luminescence in crystal phosphors

The features of the decay kinetics of radical-recombination luminescence (RRL) in crystal phosphors excited by atomic hydrogen have been studied. It is shown that the kinetics of the RRL decay can be determined both by the processes in the gas phase (decrease in the hydrogen-atom concentration as a result of their recombination at the walls of the reaction vessel after the atom-generation source has been switched off) and by the processes in the solid itself. Some conclusions are drawn concerning the mechanism of recombination for the RRL of the experimental phosphors.Translated from Izvestiya VUZ. Fizika, No. 12, pp. 16–19, December, 1973.     

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.