Recombination luminescence in KI-Tl phosphor

The X-ray luminescence and the optical scintillation of certain specimens of KI-Tl with varying activator content when excited by X-ray radiation at T=105 ° K were studied. The temperatute dependence of the brilliance of scintillation and luminescence measured under pulse conditions was found to be complex, and in the temperature range 105 °–240 ° K a series of alternating increases and decreases in these values was observed. At the same time a definite parallelism was found in the changes in brilliance of the luminescence and the scintillation. An increase in brilliance of specimens excited at 105 ° K after heating up to 133 ° K was observed and investigated. The regularities found are explained by the redistribution of hole centers. The data obtained confirm the importance of the part played by the electron-hole mechanism in the migration of the energy of the basic material to the centers of luminescence in KI-Tl phosphor.     

Temperature dependence of the ultraviolet radiation of zinc sulfide

A study is made of the cathode luminescence of zinc sulfide of various modifications and structural forms in the temperature range 80–400°K. Laws and temperature coefficients of the shift of the resonance and edge luminescence bands are obtained for perfect specimens and for specimens with stacking defects.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 11, pp. 77–85, November, 1972.     

Temperature dependence of IR band strength for polyethylene

IR spectra at 150° K and detailed temperature curves for 150–310° K for the 965, 985, 1175, 1890, and 2010 cm^–1 bands are reported. The background bears a direct relation to temperature, whereas the bands have a negative temperature coefficient of intensity. The weakening of the 944 cm^–1 band is irreversible.     

Cathodoluminescence of ZnS single crystals subjected to thermal annealing in vapors of the constituents

The 77°K cathodoluminescence spectra of ZnS single crystals grown from the melt and annealed in vapors of the constituents were studied in the spectral region 360 to 550 nm. The single crystals contained oxygen whose phase state could be changed by thermal annealing. The effect of oxygen in the ZnS lattice on the appearance and intensities of various bands in the zinc sulfide spectrum was investigated. It turned out that the bands at 390–400 nm, 410–430 nm, and 500–525 nm are associated with the luminescence of a solid solution of ZnS· O in the lattice. The intensity of the green luminescence was a function of oxygen concentration in precipitates of the solid solution on dislocations. The luminescence in the 363 to 370 nm region is associated with zinc oxide which separates from ZnS containing various amounts of sulfur.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 84–88, May, 1975.     

Tunneling Processes and Anomalous Fading in Natural Feldspars Extracted from Quaternary Deposits

Reasons for a temporal decrease (fading) in the accumulated energy in feldspars used as paleodosimeters are considered. The tunneling processes capable of leading to fading as well as temperature and time dependences of tunnel afterglow have been studied in detail. It is shown that this glow bears no direct relation to the possible tunnel depletion of the dosimetric trapping centers. With a view toward directly observing tunneling from these centers, the temperature dependences (from −200°C to +100°C) of the intensity of the luminescence stimulated in the IR band with λ ≈ 900 nm (of the optically stimulated luminescence (OSL) signal) have been studied in detail. Within the limits of sensitivity of the equipment used, tunneling from the dosimetric centers has not been detected. It has been inferred that in fading of the OSL signal, an essential role can be played by the traps that are depleted at 200°C and have a lifetime of about 2 years at room temperature.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 2, pp. 207–212, March–April, 2005.     

Photoluminescence of polycrystalline cadmium sulfide films at 77 °K

The absorption, reflection, emission, and luminescence spectra of polycrystalline cadmium sulfide films have been studied at 77 deg K at 4500–5500 A. The films were prepared by sublimination of the powder in argon, hydrogen sulfide, or vacuum, followed by crystallization on a heated or unheated substrate.Specimens deposited on substrates below 350 deg C had simple absorption and emission spectra no matter which medium was used, but ones coated on substrates above 350 deg C had absorption, reflection, luminescence, and emission spectra with fine structure, which was due to transitions between the 5s²¹S₀ ground state and 5s5p³P₁, 5s5p³P₂, and 5s5p³P₀ excited states of atomic excess cadmium.Four maxima were found in the excitation spectrum of the blue luminescence (4545, 4605, 4670, and4740 A). The spectrum of the luminescence is independent of exciting wavelength in the range 2200–4900 A.This structure was observed only for films with hexagonal lattice symmetry.     

Dielectric relaxation in Ih ice

Relaxation processes in Ih ice are studied in the temperature interval 77–27G°K and frequency band 5 Hz–500 kHz. A new maximum in thermally stimulated currents was found at 97°K, clarifying the nature of the relaxing defects. The parameters of the peaks of the thermally stimulated currents at 97, 127, 139, and 158°K are determined, and the concentrations of L defects and oriented H₂O dipoles are evaluated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 72–76, October, 1986.     

Structural and certain magnetic characteristics of (Y1−xSmx)Fe2 quasibinary system

In the present work, the character of changes of structural characteristics of (Y_1–xSn_x)Fe₂ ferromagnetic alloys is established as a function of temperature between 290°K and 770°K and of concentration for 0 <= x <= 1.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 50–53, February, 1984.     

The effect of measurement temperature on the thermo-emf and electrical resistivity of some homogeneously graphitized carbonaceous materials

This paper gives the results of measuring the temperature dependence of the thermo-emf and electrical conductivity of petroleum cokes which had undergone heat treatment at 1700–2700 ° K. The temperature dependence was studied in the range 300–1100 ° K. The experimental data are discussed in the light of existing ideas on the theory of graphitization and of the band structure of carbonaceous material.The authors wish to express their gratitude to Professor N. F. Kunin for his constant interest in their work.     

Low-temperature diffusion of silicon atoms in the nickel-nickel silicide-silicon system

The diffusion of Si atoms from a silicon substrate through a layer of nickel monosilicide into a Ni film is investigated in the temperature interval 470–670°K by the method of radioactive isotopes. The distribution profile of Si in NiSi and Ni is derived. The GB-diffusion parameters of Si in NiSi are determined. It is shown that when T>570°K there is an increase in the thickness of the initial NiSi layer, and a kink appears on the in D=f(1/T) curve. The associated change in the activation energy of diffusion from 0.43 (470–570°K) to 0.72 eV (570–670°K) is explained by the formation of Ni-Si and Si-O type complexes. The diffusion of silicon atoms accompanied by complex-formation processes determines the evolution of the resistivity of the Ni-NiSi-Si contact.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 78–83, March, 1985.     

Electrical conductivity and photoconductivity of single crystals of lithium hydride

Nonactivated LiH crystals and crystals of LiH with Mg, In, Tl, Sn, Sb, and Bi impurities are investigated. Photoconductivity is found in luminescent crystals. The temperature dependence of the electrical conductivity and photoconductivity in the temperature range of 100–570 ° K is measured. Volt-ampere characteristics of the dark current and photocurrent in fields up to 10⁴ V/cm at various temperatures are obtained. Data is presented on the inertia of the photocurrent and its dependence on the intensity of the exciting light. Conclusions are drawn concerning some connection of LiH photoconductivity with the type of activating impurity, the absence of a connection with the brightness of the luminescence, and the specific role of photoconductivity in color centers.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 10, pp. 94–98, October, 1971.     

Spin resonance of irradiated luminescent LiH crystals

ESR line width and strength are reported for crystals exposed at room temperature to the unfiltered light of a SVD-120 mercury arc and to the electrons from a betatron operated at 8–10 MeV. There is a knee in the fall in the intensity and in the increase in the line width at 90 °–120 ° C (g = 2.001 ± ± 0.001) for crystals showing blue fluorescence. The relation of the ESR spectrum to the optical absorption and to the luminescence centers is discussed.We are indebted to M. D. Lemberberg for assistance in recording the optical absorption spectra of LiH.     

Bulk and near-surface annealing behavior of the 0.8 eV luminescence in semi-insulating gallium arsenide

An annealing study of the 0.8 eV photoluminescence band in LEC GaAs has been performed, using a combination of 10 min annealing steps over a temperature range of 800–1100° C and one hour furnace annealing steps at 500–700° C. Results show that the defect responsible for the luminescence is stable in bulk material under all annealing conditions that have been investigated. In combination with earlier results, this demonstrates a stability of the defect to temperatures in excess of 900° C and indicates a parallel with the annealing behavior of the 0.67 eV band in semi-insulating GaAs. The observed annealing behavior is very different in the near-surface region, indicating an important role of As out-diffusion.     

Thermal annealing of defects in irradiated zinc oxide

The change with thermal annealing of the diffuse-reflection and luminescence spectra of electron irradiated polycrystalline zinc oxide was investigated. It was found that the absorption band of F^– and F^±centers increased at T<543°K and decreased at high temperatures. The change in the parameters of the exciton luminescence bands correlates with the change of absorption in the F^– and F^±bands. Absorption in the band of interstitial zinc ions decreases over the whole range of annealing temperatures. The effect of thermal annealing on the absorption in the near IR range of the spectrum was investigated. Explanation is given of the regularities established.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 60–65, September, 1985.     

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.     

Negative luminescence from mid-wave infrared HgCdTe diode arrays

A self-referencing, optical modulation technique was used to measure the negative luminescence efficiencies of an array of mid-wave infrared HgCdTe photodiodes with cutoff wavelength 4.6 μm as a function of sample temperature. The internal efficiency at a wavelength of 4 μm was 93% at 295 K, and nearly independent of temperature in the 240–300 K range. This corresponds to an apparent temperature reduction >50 K at room temperature and >30 K at 240 K. Moreover, the reverse-bias saturation current density was only 0.13 A/cm². The measured transmission and emission spectra were simulated using empirical HgCdTe absorption formulas from the literature.     

Proton channeling in silicon at various temperatures

A study was made of the channeling of 6. 72 MeV protons in a silicon crystal at 100–800 °K. The experimental dependence of the limiting channeling angle agrees with the theoretical prediction. A relation is found between the relative number of channeled protons and the temperature.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 6, pp. 60–63, June, 1970.     

Cathodoluminescence from epitaxial layers of p-Alx Ga1−xSb

The cathodoluminescence (CL) of doped and undoped layers of p-Al_xGa_1–xsb(0x0.8) grown by liquid-phase epitaxy has been investigated. Changing the composition of the solid solution resulted in emission bands having maxima between 0.77 and 1.58 eV at 77°K and between 0.72 and 1.55 eV at 300°K. It is shown that the following factors play a role in determining the luminescence intensity as a function of x: 1) the transfer of electrons to the L minimum in the conduction band; 2) a decrease in the hole concentration in the layers; 3) a decrease in the concentration of nonradiative recombination centers. The CL spectrum at 77°K contains a longwavelength band whose behavior is attributed to recombination through a level similar to the level known to be present in GaSb and believed to be caused by an intrinsic defect. The ionization energy of this level increases as x increases.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 40–46, November, 1976.     

Photoannealing of defects in irradiated zinc oxide

The change in the absorption and luminescence spectra of polycrystalline ZnO at 100°K following electron irradiation and photoannealing with. F^– and F^+-light was investigated. It was found that following irradiation, absorption bands of intrinsic point defects appear which after photoannealing are converted into bands of lower energy, tentatively attributed to complex electron centers.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 3–7, September, 1985.The authors wish to express their thanks to E. V. Komarov for invaluable help in the investigation.     

Interaction of excitons in indirect solid solutions of In1−xGaxP at high levels of excitation

The cathode luminescence spectra of GaP and solid solutions of In_1–xGa_xP (with an indirect energy band structure) obtained by liquid-phase epitaxy are investigated at T=77 and 9°K. It is established that the recombination of excitons on neutral donors and the pure exciton recombination with the participation of TA (=13±1 meV), LA (=31±1 meV), and TO (=43±2 meV) phonons. dominate in the low-temperature luminescence spectra of GaP and In_1–xGa_xP with a small concentration of photon impurities. The complex luminescence band that arises for sufficiently high levels of excitation and at T = 9°K is attributed to the luminescence of an electron-hole drop (EHD). The transformation of spectral form of the EHD band with the transition from GaP to In_1–xGa_xP is attributed to a simultaneous reduction in the contribution of the TA and TO replicas and to the appearance of a phononless component in the luminescence of the EHD.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 37–40, September, 1985.