Nuclear orientation study of the decay of204BiFe

The decay of²⁰⁴Bi nuclei (I =6⁺, T_1/2=11·22 h) oriented in an iron host was investigated on the JINR low-temperature nuclear orientation facility SPIN. The orientation parameterB ₂=1·17 (6) was obtained from the analysis of six prominent E1 gamma-transitions. From the measured normalized intensities of the gamma-rays observed some 70 values of multipole mixing ratios for the gamma-transitions in²⁰⁴Pb nucleus were determined for the first time. The spins 6, 6, 5 and 4 could be uniquely assigned to the²⁰⁴Pb negative parity levels at 3891·5 keV, 3768·4 keV, 3301·5 keV and 2338·2 keV, respectively. The spin-parity assignments of the levels at 4183·8 keV, 4094·2 keV, 3782·0 keV, 2506·9 keV and 2065·1 keV were confirmed as 6^–, 6^–, 5^–, 5^– and 5⁺, respectively. For the level at 3105·1 keV spin-parity 5^– was suggested and spinparity 7^– of the level at 2696·4 keV was called in question. The possible placements of the gammatransitions 3 1351·7 keV and 1353·4 keV in the decay scheme is discussed. The reorientation parameters for the long-living levels at 2264·2 keV (T _1/2=0·45 s) and 1273·9 keV (T _1/2= =265 ns) were determined asG ₂=0·41 (14) andG ₂=0·60 (17), respectively. For the isomeric level at 2185·7 keV (T _1/2=67·2 min) the value ofG ₂=0·88 (49) was proposed.The authors would like to express their thanks to T. I. Kracíková and M. Trhlík for the valuable discussions in the course of the evaluation of the experimental data.     

Quantized IR properties reconfirmed in the CO and SiO surface oscillators present in the surface layer of A bamboo stem

From analysis of diffusion diagrams of CO stretching band (25002180 cm^–1), bending band (800200 cm^–1) and SiO stretching band (1100700 cm^–1) measured in a skin surface layer of a bamboo stem (silicate cellulose), azimuthal directions where oscillators oriented were shown as ('=-90) _N=a·N-b, with a=28.3, 2×28, 22.7, b=25, 47.5, 10. And N=1,2.....14, N=1, .....6. N=1,2.....16. The optical activity (reflection integral) was shown for the CO stret. band as M_i(N)=a·N+b, with a=21.8, b=42 and N =1,2.....9. And for the bending band as M_i(N)=a·N² +b·N–c, with a=1.87×10¹, b=3.73×10³, c=7.06×10² with N=1,2.....9. Six stepnized fine series in CO weak reflection bands were confirmed as, and with N=1,2.....22. Mean values of the vibrational quantized states of the A, B and C-series in the SiO stretching weak band with R1.0% were shown as, (meV) with .     

Some physical properties of KCl+Pb2+ crystals

This paper presents the results of measurements of the mechanical and electrical properties of as-received pure and lead-doped crystals of potassium chloride. The critical resolved shear stress of the crystals obeys the Franks relationship in the whole concentration range. In addition, the correlation between ₀ and the Vickers hardness numberH was found and the equation is of the form ₀=k (H–H ₀). The solubility of Pb²⁺ in as-received KCl crystals was observed, from measurements of the electrical conductivity, to be low—the successive saturation of the solid solution started already in an environment of 5 mole ppm in agreement with data from the mechanical measurements. The density of cation vacancies and their mobility were represented by the following euqations ₁ T=6·25×10⁴ exp(–·75/kT) cm² K/volt. sec,n ₁=6·95×10²³ exp(–2·12/kT) vacancies/cm³ The value of 0sd46±0·02 eV was found as a rough estimate of the association energy.The authors wish to express their thanks to Professor Dr. J. Z.Damm and Ing. E.Mariani for their stimulating interest in the present work.     

The behavior of copper impurity in CdSnAs2

Single crystals of n-type CdSnAs₂ with a carrier concentration of 2 ·10¹⁷–4 ·10¹⁸ cm^–3 and mobility (3 to 6) · 10³ cm²/V ·sec were copper doped by diffusion saturation at temperatures from 400 to 570C. As a result of the study of the electrical properties of the doped crystals it was established that the copper in CdSnAs₂ is a fast-diffusing acceptor impurity. The solubility of Cu depends primarily on the donor-center concentration and has clearly a retrograde character. Low-temperature heat treatment (over the 200–400C range) of the Cu-doped specimens results in an increase in the acceptor concentration. The form of the log R(10³/T) curve indicates the existence of acceptor centers with an ionization energy of 0.05 eV in the Cu-doped CdSnAs₂ specimens.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 16, No. 7, pp. 39–44, July, 1973.     

Nonlinear refraction and nonlinear absorption of As2S3 aqueous solution

We report for the first time to our knowledge on the preparation of colloidal solution of chalcogenide semiconductor As₂S₃ by laser ablation and the measurements of its nonlinear-optical characteristics using Z-scan method at the wavelength of Nd:YAG laser radiation ( = 1064 nm, = 25 ns). The nonlinear refractive index was measured to be –7.5 × 10^–18 m² W^–1. Nonlinear absorption coefficient of chalcogenide solution was measured to be 1 cm GW^–1.     

The low temperature electric quadrupole orientation of184Ir and185Ir in rhenium

The half-lives of¹⁸⁴Ir,¹⁸⁵Ir and¹⁸⁶Ir have been determined to be 3.14(2) h, 14.4(1) h and 16.64(3) h, respectively. The quadrupole frequenciesv _Q = e²qQ_s/h of¹⁸⁴Ir and¹⁸⁵Ir in rhenium single crystal have been determined to be Q_s(¹⁸⁴Ir) = + 2.0(3) b MHz and Q_s(¹⁸⁵Ir) = +2.0(3) b MHz. Adopting the value of –3.6(2)×10¹⁷ V·cm^–2 for the electric field gradient eq at T=0 K, the values of the ground-state spectroscopic quadrupole moments of these isotopes are determined to be Q_s(¹⁸⁴Ir)=+2.0(3) b and Q_s(¹⁸⁵Ir)=–2.5(3) b. The¹⁸⁵Ir moment is only consistent with the ground state Nilsson configuration , the¹⁸⁴Ir moment is consistent with K4 with a predominant K=4 component, in disagreement with K=0,1 found for¹⁸⁶Ir. Our analysis differs in detail from the recent nuclear orientation study by Hagn et al.[1].     

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.     

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.     

Special features of the operation of an electron-ionization CO2-laser at high pressures

A study was made of the excitation of the working medium of a CO₂-laser at a pressure of up to 8 atm by an electron beam of duration 15 · 10^–9 sec. Results are given of the energy dissipation in a CO₂:N₂-13 gas medium in the whole range of pressures with E₀/p = (18–38) V /cm · mm Hg. The dependences of the time of appearance of the stimulated radiation with respect to the current pulse are given.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 40–44, April, 1976.     

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.     

Internal friction of alkali-halide crystals with small strains

A study is made of the strain-amplitude dependence of internal friction (IF) and the Young's modulus defect in alkali-halide crystals at amplitudes ₀ 10^–7-10^–6. It is found that If is amplitude-independent at room temperature but becomes dependent on strain amplitude and time when measured in an electric field and at elevated temperatures. In these cases, an asymmetric hysteretic peak is seen on the curve (₀). The peak is due to the thermally activated release of dislocations from weak pinning points as the dislocations vibrate inside ionic atmospheres. The energies of the ruptured bonds (0.03–0.11 eV) are typical of cationic vacancies.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 44–50, January, 1995.     

Transient creep during transformation in Cd-Zn alloys

Transient creep of Cd-2 wt. % Zn and Cd-17·4 wt. % Zn alloys has been studied under different constant stresses ranging from 6·4 MPa to 12·7 MPa near the transformation temperature. The results of both compositions showed two transient deformation regions, the low temperature region (below 483 K) and the high temperature region (above 483 K). From the transient creep described by the equation _tr=Bt ⁿ, where _tr andt are the transient creep strain and time. The parametersB andn were calculated. The parameterB was found to change with the applied stress from 0·3×10^–4 to 3×10^–4 and from 0·6×10^–4 to 18×10^–4 for Cd-2 wt. % Zn and Cd-17·4 wt. % Zn, respectively. The exponentn was found to change from 0·8 to 0·95 for both alloys. The parameterB was related to the steady state creep rate through the equation , the exponent was found to be 0·5 for Cd-2 wt. % Zn and 0·6 for the eutectic composition. The activation energies of transient creep in the vicinity of the transformation regions (above 483 K) were found to be 50·2 kJ/mole for Cd-2 wt. % Zn and 104·7 kJ/mole for the eutectic composition characterizing the mechanisms of grain boundary diffusion and volume diffusion in Cd, respectively.     

The dependence of the neutron temperature on the geometric parameter for water and loose diphenyl

The dependence of the neutron temperatureT _n on the geometric parameterB ² was measured by the pulse method in water and loose diphenyl. The measurements were made on a moderator poisoned by cadmium sulphate, a substance whose absorption cross-section is non 1/v.The following results were obtained: For waterT _n [eV]=–(0·00391±0·00045)B ² [cm^–2]+(0·02537±0·00035) for loose diphenyl:T _n [eV]=–(0·01014±0·00152)B ² [cm^–2]+(0·02518±0·00054).We are indebted to J. Jirou and J. Jadavan for their assistance in the measurements, the accelerator operation and electronic apparatus maintenance.     

Energy Spectra of the Local States in the Forbidden Gap of Monoclinic TlInS2xSe2(1?x) Crystals

Near IR properties of the mixed TlInS_2xSe_2(1–x) have been studied previously by the present authors. In this work the temperature and frequency dependence's of the conductivity and the current-voltage characteristics (in relatively weak electric field), have been investigated for monoclinic TlInS_2xSe_2(1–x) crystals, which are perspective materials for IR applications. From the temperature dependence's of conductivity in the direction perpendicular to c- axis the band gap E^g = 2.22 eV was determined for --TlInS₂ crystals. The impurity centres were determined located at 0.43, 0.73 eV and 0.35, 0.48, 1.12 eV for the direction of current i//c and i c, respectively. The concentration of the centres located at 0.48 and 1.12 eV were calculated to be N_A – N_D = 4.8 · 10⁹ cm^–3 and 1.9 · 10¹¹ cm^–3, respectively. It was found that in the solid solutions TlInS_2xSe_2(1–x) for 0.3 x 1, the conductivity follows the dependence (v) = ₀·^s in the temperature range between 100 to 600 K. In the temperature range of 80-400 K charge bounce plays an important role in the conductivity mechanism. Occurrence of the deep and low-levels impurity centres and a tail of the density of energy states in TlInS_2xSe_2(1–x) crystals make them perspective for practical applications: switching and memory effects, N-type current-voltage characteristics, induced conductivity etc.     

The optical absorption of hydroxyl ions associated with divalent calcium in NaCl

The measurements confirmed the association of Ca²⁺ and OH^– in NaCl: CaCl₂ + NaOH, which causes an increase and a shift +0·031 of the OH^– absorption at 2·8, the extinction of the OH^– UV-absorption at 184 nm and the occurrence of new absorption bands between 160 and 210 nm.The measurements were performed at the II. Physikalisches Institut of the University of Stuttgart.     

The vibration spectra of sodium chloride doped with Na2CO3 and NaOH

The paper investigates absorption and reflection spectra, in the infra-red region from 2 to 25, of single crystals of sodium chloride (NaCl) doped with 0·1 to 1% mol. of Na₂CO₃ and NaOH. A correlation between the absorption bands and the corresponding groups CO ₃ ^2– and OH^– was found. It was also shown that in crystals pulled in air by the Kyropoulus method from a melt doped with NaOH the latter is practically completely transformed into Na₂CO₃.The work was carried out at the suggestion of Dr. A. Bohun, whom the author thanks for valuable discussions.     

Electrical and optical properties of electron-irradiated ZnGeP2

Conclusions and summary The following conclusions are drawn from the reported study:The electrophysical properties of ZnGeP₂ crystals and their optical transparency in the range hG are attributable to the presence of a density-dominant (10¹⁷–10¹⁹ cm^–3) deep [E_v+(0.5–0.6) eV] growth defect associated predominantly with Zn vacancy clusters.Irradiation by high-energy electrons induces a shift of the Fermi level in the direction of E_G/2 and increases the resistivity of ZnGeP₂ to values of approximately 10¹² ·cm at 300 K. Irradiation with high-energy electrons is an effective technique for the optical bleaching of p-ZnGeP₂. The reversible modification of the optical absorption spectra of p-ZnGeP₂ in connection with irradiation and subsequent annealing indicates that the absorption step in the vicinity of h 0.6 eV is not attributable to light absorption by germanium inclusions, but to optical transition from the valence band to the growth-defect level E_v+(0.5–0.6) eV.Enhancement of the optical transmissivity of p-ZnGeP₂ in the range hG can be achieved in two wayss 1) as the result of a decrease in the density of centers with the level E_v+0.6 eV by variation of the growth conditions or subsequent annealing; 2) by shifting the Fermi level above the energy position E_v+0.6 eV through the irradiation-induced injection of compensating donor centers.The injection of radiation defects is an effective technique for controlling the electrical and optical parameters of the compound ZnGeP₂.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 122–130, August, 1986.     

A study of the photoluminescence of crystals of the hexagonal modification of Β-Ga2As3

The excitation and radiation spectra of-Ga₂As₃ crystals have been studied. The radiation spectrum consists of two overlapping bands (1.44 and 1.61 eV) and a very weak band in the 2.8–2.9 eV region. The temperature dependence of the halfwidth of the luminescence bands was studied and the position of the levels responsible for the luminescence were determined: E_1,v = 0.84 eV and E_2,v = 0.59 eV. These luminescence bands in -Ga₂As₃ crystals undergo thermal quenching. The kinetics of the photoconductivity and the photoluminescence were studied and it was shown that the recombination of nonequilibrium carriers occurs by two channels: via fast s levels and slow r levels, the trapping cross section of the latter being .Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 72–75, September, 1972.     

Resistivity changes of evaporated Ti films caused by sorption of O2, CO2 and H2

Resistivity changes of Ti films evaporated in UHV were measured during sorption of O₂, CO₂ and H₂ at very low pressures (p 1·6×10^–6–1·6×10^–5Pa). During the sorption process the pressure was kept constant. For O₂ and CO₂ an increase of the resistivity with a tendency to saturation was observed. For H₂ anomalous curves with a resistivity maximum and a subsequent decrease of the resistivity were obtained. Possible mechanisms of the processes are discussed. For the Ti/O₂ interaction a simple model describing the time dependence of the resistivity changes is proposed.We are indebted to dr. L. Pátý for consultations in vacuum technology and his permanent help in the experimental work and to dr. Z. Knor for a valuable discussion and for kindly extending us many references.