Determination of the Constants of Binding of Acridine Dyes with Micelles of Sodium Dodecyl Sulfate Using the Quenching of Delayed Fluorescence by Heavy Atoms

The constants of binding dye molecules with the micelles of sodium dodecyl sulfate are determined using quenching of delayed fluorescence of acridine dyes by sodium iodide in aqueous–micellar solutions. Kinetic equations have been composed that describe the processes of deactivation of the excited states of dyes. By solving these equations at the concentration of the quencher sodium iodide corresponding to the minimum lifetime of triplet states and at the concentration of micelles corresponding to the least value of the delayed fluorescence quenching rate constants, we obtained the constants of binding dyes with micelles equal to 1.3·10⁷, 2.9·10⁷, and 3.1·10⁷ M^–1 for trypaflavine, acridine orange, and acridine yellow, respectively. We calculated the rate constants of quenching of the triplet states of the molecules of dyes by iodide ions (I ^–) that decreased in transition from trypaflavine to acridine orange and acridine yellow.     

Experimental pressure dependence of the accelerated current in the chamber of the sirius synchrotron

An experimental study of the dependence of the accelerated charge in the synchrotron on the vacuum-chamber pressure is reported. The results are compared with calculations; in the pressure range 5 · 10^–6–2 · 10^–5 torr, the experimental and calculated results agree well.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 12, No. 2, pp. 31–35, February, 1969.The authors thank P. P. Krasnonosen'kikh for assistance in the experiments and G. P. Fomenko for discussion of the results.     

Diffusion coefficient of selenium in indium antimonide

The diffusion of selenium in indium antimonide has been studied in the temperature range 400–490°C, by the method of removing layers. Two regions have been distinguished in the donor distribution profiles. The first has a low diffusion coefficient and a high surface concentration, near to the limit of solubility of selenium (8·10¹⁸ cm^–3). In the second region, a much larger diffusion coefficient and a surface concentration lower by two orders of magnitude (8·10¹⁶ cm^–3) with weak temperature dependence are found. The temperature dependences of the diffusion coefficients of the first and second regions can be described by the expressions: D=4.8·10¹³ exp(–4.1 eV/kT) cm²/sec, D₂=1.9·10¹³ exp(–3.9 eV/kT) cm²/sec.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 40–43, November, 1991.     

In-plane magnetic surface anisotropies in Fe(110)

In-plane magnetic surface anisotropies have been detected for Fe(110) on W(110) using in situ Conversion Electron Mössbauer Spectroscopy (CEMS). The phenomenon used for the determination of this anisotropy was a switching of the spontaneous magnetizationJ _s from [001] to [1¯10] with decreasing thickness. Analysis of the data is performed using a homogeneous magnetization approximation for competing surface and bulk anisotropies, which is justified by a micromagnetic analysis and established experimentally by CEMS. In-plane surface anisotropy constants for the clean Fe(110) surface, the Fe metal-interface and the FeGaAs interface are determined toK _s,p ^FeUHV =0.065 erg·cm^–2,K _s,p ^FeMetal =0.040 erg ·cm^–2, andK _s,p ^FeGaAs =0.047 erg ·cm^–2, all with an estimated accuracy of the order of 10%.     

Structure and electrical properties of thin films of copper selenide

Electron-diffraction and electron-microscope methods were used to investigate the structure of Cu₂Se films of close to stoichiometric composition. It is shown that in polycrystalline and single-crystal films of thickness >400Å at room temperature, the tetragonal modification is stable, which at temperatures above 400°K is transformed into the cubical modification. In thinner films d<400 Å the cubical modification of copper selenide is stable at room temperature. A sharp peak is observed at 400°K on the temperature dependence of the resistance; this is connected with the phase transition. At room temperature, copper selenide is a degenerate p-type semiconductor with carrier concentration 5 · 10²²–8 · 10²⁰ cm^–3, depending on the thickness of the film.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 90–94, August, 1973.     

Anomalous plasma phenomena of hollow cathode arc discharge

Magnetically confined argon plasma produced by hollow cathode arc discharge has been studied in different experimental conditions, with discharge current from 10–50 A, vessel argon pressure between 10^–3 and 10^–4 torr (1 torr=133·32 Pa) and axial magnetic field up to 0·12 T. The plasma density measured by a cylindrical Langmuir probe is found to be 10¹⁹ to 4 × 10¹⁹ m^–3 and the electron temperatureT _e varies between 2·5 and 4·8 eV. When an external axial magnetic field is applied the plasma temperature decreases with the increase in the magnetic field intensity until it reaches a minimum value at 0·075T and then increases with the same rate. This has been interpreted as high frequency waves excitation due to electron beam-plasma interaction, which explains the electron density jumps with the magnetic field intensity. Enhanced plasma transport across the magnetic field is studied and classified as anomalous diffusion.     

Elastic constants of the alloys Cd1−x Zn x (x<0.3%) and their temperature dependence

The temperature dependence of elastic constants of Cd_1–x Zn _x alloys, havingx=0.021, 0·042 and 0·233 at.%, has been measured in the temperature range from 4·2 to 300 K by the pulse-echo-overlap ultrasonic method. The adiabatic compressibilities and the Debye temperatures have been calculated. All elastic constants with the exception ofc ₄₄ increase slightly with the growing concentration of Zn.The summary of this paper was presented on the 7^th Conference on Ultrasonic Methods in ilina, September 11^th–13^th, 1980.     

Photoinduced Electron Transfer From Carbazole to Halomethanes in a Gas Phase

Intermolecular photoinduced electron transfer (PET) in a gas phase was studied using carbazole vapor fluorescence quenching by halomethanes (CHCl₃, CH₂Br₂, CCl₄, CHBr₃). The fluorescence quenching rate constants k _q changing from 2.3·10⁵ sec^–1·torr^–1 in mixtures with CHCl₃ to 4.6·10⁶ sec^–1·torr^–1 in mixtures with CHBr₃ at a constant temperature of 403 K were estimated. The dependence of the carbazole fluorescence decay rates in the presence of halomethanes on the free energy change G during transfer of the electron from carbazole to halomethanes is considered. It is suggested to take into account the influence of the vibrational energy of the carbazole molecule E _vib and its temperature changes in estimation of the G values. The differences between PET in the gas and liquid phases were analyzed. It is found that for mixtures with CCl₄ and CHBr₃ the negative temperature dependence of k _q is observed, when the decay rates and efficiencies of the intermolecular PET decreased with temperature increase in the range 403–573 K, i.e. these mixtures the electron transfer is not a barrier-restricted process.     

Nuclear spin lattice relaxation of58CoFe and60CoFe measured by the thermal cycling method

Thermal cycling of thin foil samples is used to measure nuclear spin lattice relaxation of dilute⁵⁸Co and⁶⁰Co in iron at polarizing fields up to 1.3 T. The relaxation rates for the two isotopes differ by a factor of 7.1; the good agreement between the high field values for ² C ₂, (2.93±0.15)·10¹⁵ K·s^–1·T^–2 (⁵⁸Co) and (3.01±0.06)·10¹⁵K·s^–1·T^–2 (⁶⁰Co) verifies the reliability of the experimental method. An enhancement factor model is introduced and shown to give an excellent reproduction of the observed field dependence of the relaxation.     

Characteristic diffusion constants of cadmium in silicon

This investigation was devoted to experimental determination and analysis of curves describing the diffusive distribution of cadmium in silicon at different levels of prealloying of the silicon with phosphorus and different temperatures of isothermal diffusion, with allowance for the characteristic exponential relation between the pre-exponent D₀ and the activation energy Q. Numerical values of D_k and Q₀ were found. They are equal to 4·10^–8 cm² · sec^–1 and 0.22 eV, respectively.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 65–68, November, 1984.     

Spectral Properties of Single Crystals of Synthetic Diamond

The half-width of the spectrum of Raman scattering (RS) of the first order of a diamond single crystal grown in a nickel-free system containing nitrogen getters is identical to all growth sectors (1.69 ± 0.02 cm^–1). The sectorial inhomogeneity is not reflected in the transmission spectra and birefringence of this crystal. The nitrogen concentration is 4·10¹⁷ cm^–3. For different growth sectors of the diamond crystal grown in the Ni–Fe–C system, the half-width of the Raman line varies from 1.74 to 2.08 cm^–1, differences in the transmission spectra and birefringence are observed, and photoluminescence is revealed. The concentration of nitrogen in the growth sectors {001} is 1.6·10¹⁹ cm^–3, the content of nickel is estimated to be at a level of 10¹⁹ cm^–3, and the content of nitrogen in the {¯111} sectors is 4·10¹⁹ cm^–3.     

Properties of MOS-structures based on anode-oxidized CdSnAs2

The properties of metal (Al, Au)-anodic oxide-CdSnAs₂ monocrystal structures are studied. It is established that MOS-structures using undoped CdSnAs₂ crystals show a high positive fixed charge in the anodic oxide (N_S 5·10¹² cm^–2) and high surface state density on the oxide-CdSnAs₂ boundary surface (N_SS 2·10¹³ cm^–2·eV^–1). In MOS-structures using diffusion-doped (copper) crystals the sign of the fixed charge is negative (N_S 10¹¹ cm^–2, N_SS 2·10¹² cm^–2·eV^–1). The latter structures show a definite photosensitivity and photomemory. The possibility of effective control of the fixed charge value within the oxide by illumination is shown. The surface state distribution over energy, time constant, and capture section is determined.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 90–93, September, 1982.     

Surface strain-hardening of iron alloys with an intense pulsed electron beam

Results are presented from study of surface strain-hardening and measurements of the structure of carbon (St. 45, U7A, 40Kh) and alloy (R6M5, Kh6VF) steels subjected to surface fusion by pulsed electron beams with the following parameters: electron energy 20–250 keV, pulse duration 5·10^–8–3·10^–4 sec, power density 10⁵–10⁹ W/cm³. It is shown that the microhardness of the surface of most alloys increases by a factor of 1.2–1.7 on quenched specimens and by a factor of 2.5–3.5 on unquenched specimens, depending on the regime. Microhardness increases in the surface layer due to quenching from the liquid state. An increase in electron energy from 40 to 250 keV with a pulse duration of 6·-10^–8 sec leads to a severalfold increase in the thickness of the strengthened layers and to a shift of the microhardness peak from the surface to a depth of 70 m. Here, microhardness reaches 2000 kgf/mm². This is due to an increase in the mean free path of the electrons in the metal and displacement of the energy-release maximum of the bundle deeper into the specimen.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, No. 6, pp. 38–43, June, 1985.     

Some superconducting properties of 25%Nb–75%Zr alloy

The manner of preparation of superconducting 25% wt Nb–75% wt Zr wires is described. Short samples of these wires were measured in static magnetic fields up to 80·5 kG and the authors describe the method of these measurements. The paper gives the results of measuring the critical current density dependence on the external perpendicular magnetic field for both cold-worked wires with different deformations and heat-treated wires. The dependence of the critical current density on the heat treatment temperature after wire deformation for different magnetic fields was obtained. The optimum heat treatment temperature (vacuum better than 10^–3 torr, 1 hour) is 450–600C for magnetic fields 0–80·5 kG. The values ofi _c of these wires in magnetic fields up to 60 kG are the same or higher than those of 75% Nb-25% Zr wires, and in fields above 60 kG they are much higher.     

Decay of tripositronium to an electron and two photons

The bound state of a positron and two electrons, called tripositronium, is investigated in this article. The differential probability is calculated for the decay of the ground state of tripositronium to an electron and two photons. It is established that such a decay primarily occurs with the formation of a nonrelativistic electron. It is shown that the integral decay probability is equal to 0.15 · 10⁹ sec^–1. This corresponds to a lifetime for tripositronium of 0.65 · 10^–8 sec.Translated from Izvestiya Vysshikh Uchebnykh Zavedeoii, Fizika, No. 4, pp. 69–73, April, 1978.The author thanks V. S. Vanyashin for formulating the problem and for useful discussions.     

Electrical properties of p-type ZnGeP2 irradiated by H+ ions

The properties of p-type ZnGeP₂ [p₀=(5–10)·10¹⁰ cm^–3, ₀=(2–5)·10^–7 (·cm)^–1], irradiated with H⁺ ions [E=5 MeV, T_irr=300 K, D=(1·10¹²–1.7·10¹⁶) cm^–2] are studied. An increase in the resistivity (to gr_max - 5·10¹¹ ·cm) and subsequent reduction in for large currents of H⁺ ions ( - 9·10⁸ ·cm for D - 1.7·10¹⁶ cm^–2), is observed in irradiated crystals. The resistivity of irradiated p-type ZnGeP₂ is found to be very sensitive to hydrostatic pressure [(4–5)·10^–5 bar^–1]. The annealing of radiation defects in the temperature interval (20–600) °C is examined.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 91–93, October, 1991.     

ГЕНЕРАТОР ВЫСОКОВОЛ ЬТНЫХ ИМПУЛЬСОВ МАЛО Й ДЛИТЕЛЬНОСТИ С МАЛЫМ ВРЕМЕНЕМ НАРАСТАНИЯ И ЕГО ПРИМЕНЕНИЕ ДЛЯ И ЗМЕРЕНИЯ ПОДВИЖНОСТ ЕЙ ЭЛЕКТРИЧЕСКИХ ЗАРЯД ОВ В ГАЗАХ

The paper describes a generator of square-wave power pulses with a front of 2×10^–8 second and length of 0·6×10^–6 sec for a capacity load of 70 pF, with continuously regulable amplitude from 1 to 9 kV. The current in the pulses >100 A. The delay in the high-power pulse with respect to the triggering pulse does not exceed (0·09–0·15)×10^–6 sec. The generator is intended for operating spark counters of relativistic particles although its range of use may be much greater. The paper points out its use for studying the mobilities of electric charges in gas mixtures of spark counters.     

Formation of zirconium dioxide in molybdenum alloy tsm-6

The formation of zirconium dioxide was observed during annealing of deformed molybdenum alloy TsM-6. Particles of ZrO₂ are formed in former subboundaries, grain boundaries, and within the grains. The size, shape, and distribution of particles at different depths after annealing at different temperatures were determined. The crystallographic orientation of ZrO₂ particles in relation to the matrix was determined. The results indicate penetration of oxygen into the alloy during annealing (in vacuum of 1 · 10^–4 to 7 · 10^–5 mm Hg) through enrichment of the subboundaries in oxygen and internal oxidation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 107–112, August, 1973.Our thanks to A. D. Korotaev, on whose initiative this work was undertaken.     

The ESR spectrum of oxygen vacancies in sodium tellurite glasses

A theoretical analysis is presented for the shape of the ESR spectrum of the radiation-induced centers of oxygen vacancy type in sodium tellurite glasses. It is found that a qualitative agreement between the theoretical and observed curves can be obtained only if one assumes a completely anisotropic g factor and an inhomogeneous structure for the paramagnetic centers, whose parameters are found as g_x = 1.930; g_y = 1.971; g_z = 2.046; x ² >=4–10^–4-2.5·10^–3; y ² > = 4.9·10^–8-1·10^–6; z ² > = 2.2·10^–4-9·10^–4; d ² > = 36–100 G². It is concluded that the glass composition affects the center nonuniformity.Translated from Izvestiya VUZ, Fizika, No. 3, pp. 63–68, March, 1973.     

Radial distribution of the electron concentration in a rotating plasma with the help of an interferometer

Results of experiments on the investigation of a plasma rotating in crossed electric and magnetic fields are presented. The radial electron concentration distributions in a nitrogen plasma at pressures varying from 8·10^–2 to 3·10^–1 mm Hg are obtained with the help of a 3.39 m laser interferometer. The effect of the magnitude of the magnetic field on the form of the radial distribution is determined.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 72–75, January, 1982.