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1.
Results of an investigation of the characteristics of a transverse discharge with prebreakdown ionization multiplication of electrons in the working media of N2(C-B)-and SF6/H2 chemical HF-lasers are reported. The conditions of initiation of a stable volume discharge in the discharge gap with low homogeneity of the electrical-field distribution are investigated. A quasisteady plasma based on N2 molecules with a radiation duration of ≤0.5 μsec at transitions of the 2+-system and a homogeneous discharge in a SF6/H2=(3–7)/(1–2) kPa mixture, which is of interest for preionization of the working medium of an HF-laser by the predischarge method, are obtained. Uzhgorod State University, 46, Pidgirna Str., Uzhgorod, 294000, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 3, pp. 412–415, May–June, 1999.  相似文献   

2.
We measured the dispersion of light in thin Y2O3 films in the visible and near UV regions of the spectrum. The spectrum of edge absorption is investigated. We found the parameters of a single-oscillator approximation and determined the dispersion energy and the ionicity of bonding. I. Franko L’vov State University, 50, Dragomanov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 5, pp. 651–654, September–October, 1997.  相似文献   

3.
The processes of crystallization by the method of liquid epitaxy are studied for the first time for single-crystal films of CdWO4 doped with the mercurylike ions Bi3+ and Pb2+, which can be used as thin-film components of combined scintillators for monitoring α- and β-activities. It is shown that in comparison with their solidcrystal analogs, the special features of these films consist in a longwave shift of the integral luminescence spectrum that is caused by high concentrations of the radiating complexes (VCd-WO6) with hvmax=2.05–2.15 eV and the “distorted” complexes (WO6)* in them. It is found that in the case of luminescence of single-crystal films CdWO4:Pb, radiation of mercurylike centers (PbO6) prevails with hvmax=2.87 eV, while in luminescence of CdWO4, radiation of centers (BiO6) with hvmax=2.16 eV and of complexes (VCd-WO6). Institute of Applied Physics, Iv. Franko Lvov State University, 49, General Chuprynka St., Lvov, 290044, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 2, pp. 211–215, March–April, 1998.  相似文献   

4.
Conclusions The studies performed here have shown that the superlattice samples studied exhibit photoluminescence spectra which agree with the Kronig-Penney model, although in calculating the energies of the radiative transitions it is necessary to take into account the binding energy of the excitons,E B. Due to the exciton—phonon interaction, the 1HH peak breaks up on the long wavelength side into a Poisson distribution. The energy of the LO phonon so determined is 34 meV. Bands due toD 0-A 0 andD 0X transitions, caused by remaining low-level impurities in the GaAs crystals are also observed. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 61, Nos. 3–4, pp. 241–245, September–October, 1994.  相似文献   

5.
Angeli  I. 《Hyperfine Interactions》2001,136(1-2):17-24
Experimental Coulomb isotope shifts δE Coul from K α transitions, and radius differences δ〈r 2 eμ measured by electron scattering and muonic atom X-rays were used to derive ‘experimental’ coefficients C 1,exp for 54 isotope pairs of 18 elements from Mo to U. A χ2-analysis shows that these experimental coefficients are – on average – 3.5% lower than the theoretical C 1 values calculated by Seltzer, or more precisely: C 1,exp=0.965(± 0.014)×C 1. The need for more accurate theoretical calculations is stressed, and consequences of this deviation are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

6.
Energetis of interchromophore interactions in a covalently bound prophyrin-chlorine heterodimer (Por-O-Chl) is investigated at temperatures from 77 to 293 K in solvents with differing polarity (toluene, tetrahydrofurane, and diethyl ether: petroleum ester: isopropanole=5∶5∶2 mixture). We substantiate the conclusion that the strong quenching of fluoresence and phosphorescence of the porphyrin fragments in both stable isomers of the Por-O-Chl heterodimer is induced not by the photoinduced charge transfer but rather by efficient processes of singlet-singlet (probability FSS=1.3·1011 to 6.8°1010 sec−1) and triplet-triplet (probability FTT≥108 sec−1) radiationless electronic excitation transfer. It is shown that the S−S transfer takes place without quantum losses from the thermodynamically equilibrated S1 state of the donor, and its dynamics and main regularities at temperatures from 77 to 293 K are described by the inductive resonance theory without any additional asssumptions. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp. 75–82, January–February, 1998.  相似文献   

7.
Photoinduced electron transfer (PET) in a Pd-porphyrin-quinone complex (Pd-P-Q) was investigated using the flash photolysis method in microsecond and picosecond range and by luminescence. The investigations were performed for toluene solutions. Intramolecular PETs in the lower excited singlet state (kCT=1.7·1010 sec−1) and in the triplet state (kCT=2.5·108sec−1) were observed. For a quantum yield of the triplet state that is close to 1 in Pd-porphyrin (Pd-P) this yield is equal to 0.4 in Pd-P-Q. This decrease is the result of PET in the excited state and, possibly, in an unrelaxed triplet state. Triplet Pd-P-Q molecules were efficiently quenched by unexcited molecules, and this process is related to intermolecular charge transfer. This electron transfer is likely to occur from the Pd-P protion of an excited molecule to the quinone protion of an unexcited molecule in the collisional complex (Pd-P-Q)2. Charged radicals, formed once the collisional complex is transferred and separated, have a wide absorption band with a maximum of about 960 nm. The average lifetime of the radicals was about 2 msec. Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No 1 pp. 61–70, January–February, 1997.  相似文献   

8.
A monocrystal ofFe 3 O 4 is characterized by resistance, magnetoresistance and magnetic measurements in a temperature range from 4.2 K to 350 K and magnetic field-cycling from −9 T to 9 T. The resistance measurements revealed a metal-insulator Verwey transition (VT) atT v =123.76 K with activation energy E=92.5 meV at T >T v and temperature-substitute for the activation energy below the VT,T 0=E/k B ≈3800 K within 70 K–110K. The magnetotransport results independently verified the VT at 123.70 K, with discontinuous change in the magnetic moment ΔM≈0.21 ΔM≈0.21μ B and resistance hysteresis, dependent on the magnetic field in a narrow temperature range of 0.4° around theT v . The magnetic characterization established self consistentlyT v as ≈123.67 K, the jump in the magnetization at the VT≈0.25μ B and confirmed, that the magnetocrystalline anisotropy is the main microscopic mechanism responsible for the magnetization of the monocrystal (88%) with additional natural and imposed defects contributing as 12%.  相似文献   

9.
Based on the measured spectra of the action of the process of cis-trans-NH(ND)-isomerization of 5-cyano-2,2,8,8,12,13,17, 18-octamethylisobacteriochlorin (H2-COMiBCh) and its deuteroderivative (D2-COMiBCh) in polycrystalline matrices of n-octane and r hexale at 4.2 K, it is established that the character of embedding of COMiBCh in the matrices of n-alkanes has a substantial effect on the barrier of dark rearrangement and the rate of photoinduced NH(ND)-rearrangement, while deuteration of the center of a molecule shifts the dynamic equilibrium toward a trans-form in photoexcitation. To whom correspondence should be addressed. Reported at the VIIIth International Conference on Spectroscopy of Porphyrins and Their Analogs, Minsk, September 22–26, 1998. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina, Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 555–559, July–August, 1999  相似文献   

10.
Magnetic nanoparticles of cobalt ferrites Co x Fe3−x O4 (x = 1 or 2) have been obtained either by mechanical milling or thermal treatment of pre-prepared layered double hydroxide carbonate x-LDH–CO3. Mechanical milling of the 1-LDH–CO3 leads to the large-scale preparation of nearly spherical nanoparticles of CoFe2O4, the size of which (5 to 20 nm) is controlled by the treatment time. Core-shell structure with surface spin-canting has been considered for the nanoparticles formed to explain the observed hysteresis loop shift (from ZFC–FC) in the magnetic properties. Annealing treatment of the 2-LDH–CO3 below 673 K results in the formation of nearly spherical pure Co2FeO4 nanoparticles. At 673 K and above, the LDH decomposition leads to the formation of a mixture of both spinels phases Co2FeO4 and CoFe2O4, the amount of the latter increases with annealing temperature. Unusually high magnetic hardness characterized by a 22 kOe coercive field at 1.8 K has been observed, which reflects the high intrinsic anisotropy for Co2FeO4.  相似文献   

11.
The electronic structure of La1–x Ga x MnO3+δ. solid solutions is studied by X-ray photoelectron spectroscopy (XPS). The valence state of the manganese is estimated by various methods: by analyzing the difference in the binding energies of the Mn2p3/2 and O1s electronic levels, analyzing exchange splitting in the spectrum of Mn3s, and from the dependence of the binding energy of the XPS spectrum of Mn2p3/2 on the calcium concentration. The state of oxidation of the manganese in the compositions containing calcium lies between Mn3+ and Mn4+. The efficacies of these methods are compared. A correlation is found between the type of crystalline structure of La1–x Ga x MnO3+δ. (0 ≤ x < 1) and the binding energy of the Mn2p3/2 peak. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 419–427, May–June, 2009.  相似文献   

12.
The Jones–Dole B coefficients of the electrolyte Lithium bromide (LiBr), reference salts tetra butyl ammonium tetra phenyl borate (BU4NBPh4), tetra butyl ammonium bromide (BU4NBr), and potassium chloride (KCl) in dimethylsulfoxide (DMSO), water, and DMSO–water mixtures were obtained at different temperatures range from 25 to 45 °C For this, the relative viscosities were measured for Lithium bromide (LiBr) and reference salts in DMSO, water, and DMSO–water mixtures at above-mentioned temperatures. The B coefficients of these electrolytes were behaved as structure makers in DMSO, while in H2O and DMSO–H2O mixtures, the B-coefficient values were less positive showing the weak structure-making effect. Ionic viscosity B coefficients allow us to assess the behavior of ions in the solvent mixtures. In this study it was observed that all the values of ionic B coefficient of (Li+) were positive and small showing the weak structure-making effects. It was also observed that Br ions maintain negative B coefficient values in all DMSO–H2O mixtures, except in 60% DMSO mole fraction. From this it can be concluded that Br ion behaved as a structure breaker in water and in all DMSO–H2O mixtures except in 60% DMSO mole fraction mixtures. The low B ± values of alkali metal ions and Br ions in water are due to the breakdown of the tetrahedral structural of water and the formation of strongly structured solvated ion. It is also observed that the values of the energy of activation of the flow for LiBr are greater in DMSO–water mixtures and in pure water than in DMSO. This may be due the presence of a network of hydrogen bonds which cause the hindrance in the flow of the solution of LiBr in DMSO–water mixtures and in pure water than in DMSO.  相似文献   

13.
Pseudoelasticity caused by pseudotwinning in short-range ordered In-Pb alloys (6, 8 and 11.6 at. % Pb) is studied in the temperature range 0.48–180 K. The mechanical hysteresis parameters, namely, the thermodynamic stress τ T which provides the reversibility of plastic deformation and the frictional stress τ f which characterizes the resistance offered by crystal lattice and its defects to twin boundaries motion are estimated. It is found that athermal processes determine the reversible deformation: the mechanical parameters τ T and τ f do not depend on temperature and strain rate. The stress τ T increases and the stress τ f decreases with increasing Pb content. One of the main conditions of the exhibition of superelasticity is the fulfillment of the inequality τ T f .  相似文献   

14.
The nonlinear dynamics of a waveguide CO2 laser with combined periodic loss and pumping modulation is investigated theoretically and experimentally. The possibilities of controlling time and energy parameters of the output radiation using the corresponding selection of the detuning of the cavity's longitudinal mode from the center of the amplification line, the amplitude, and the frequency of loss modulation are demonstrated. The observed asymmetric dependence of the lasing-radiation density on the detuning of the cavity frequency is explained by the attendant modulation of the refractive index of the loss modulator. To whom correspondence should be addressed. B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 68, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 471–478, July–August, 1999.  相似文献   

15.
I present a brief overview of measurements and calculations that establish the unitarity of the Cabibbo–Kobayashi–Maskawa matrix. I also discuss two experimental programs related to checking the unitarity of the CKM matrix: one tests isospin-breaking corrections using T=2 decays; and the other is an experiment to measure the beta asymmetry from polarized Ultra-cold Neutrons (UCNs), which could yield an accurate determination of V ud with different systematic uncertainties than existing data. Supported by the U.S. Department of Energy.  相似文献   

16.
We have used EPR to study the effect of γ radiation on calcium sulfite. We have observed and identified the radiation-induced radical ions SO 2 (iso) with g = 2.0055 and SO 2 (orth-1) with g1 = 2.0093, g2 = 2.0051, g3 = 2.0020, identical to the initial and thermally induced SO 2 respectively, SO 3 (iso) with g = 2.0031 and SO 3 (axial) with g = 2.0040, g = 2.0023, identical to mechanically induced SO 3 . We have established the participation of radiation-induced radical ions SO 3 in formation of post-radiation SO 2 . __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 467–472, July–August, 2006.  相似文献   

17.
The influence of changes in the refractive indices of the active medium and the loss modulator on the amplitude-detuning characteristic of a CO2 laser was theoretically investigated. It is shown that at a comparatively great magnitude of sweeping the “instantaneous” lasing frequency, the magnitude of the laser response increases not only in negative detunings, but also over a wide range of positive detunings. The use of the procedure of changing the magnitude and sign of detuning as well as the range of sweeping and the frequency of modulation makes it possible to realize various periodic and chaotic regimes of lasing, i.e., to exercise control over the time and energy parameters of pulses over a very wide range. B. I. Stepanov Institute of Physics of the Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 318–324, May–June, 1997.  相似文献   

18.
The band at 896 cm−1 in the Raman spectrum of acetic acid consists of at least two lines (873 and 896 cm−1) whose intensities and depolarization factors differ strongly. A temperature increase leads to an increase in the intensity of the 873-cm−1 line as compared to the intensity of the 896-cm−1 line. Dilution of the acid with acetonitrile leads to a similar but much more pronounced effect. In solutions with CCl4 and water, the relative intensity of the low-frequency line decreases; in aqueous solutions, the width of the 896-cm−1 line passes through a maximum with 0.4 mol. fractions of the acid (for this concentration, the line width is larger by a factor of 2.5 than in a pure liquid), while in the solutions with CCl4 it decreases smoothly (almost twofold with strong dilution: 0.05 mol. fractions). Experimental data are in agreement with the assumption that the 873- and 896-cm−1 lines refer to the vibrations of the same atoms in a molecule and to associates with a free and an H-bonded atom of the oxygen of a C=O group, respectively. The difference in the frequencies and depolarization factors of the lines causes the differences in the distribution of an electron cloud in the molecule. To whom correspondence should be addressed. Alisher Navoi Samarkand State University, 15, Universitetskaya Str., Samarkand, 703004, Uzbekistan. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 467–470, July–August, 1999.  相似文献   

19.
The Ba2In2 − x Sn x O5 + x/2 solid solution was confirmed up to x = 1 by solid-state reaction. X-ray diffraction at room and at elevated temperatures, Raman scattering and impedance spectroscopy were used to characterise the samples. The structure refinement of the composition x = 0.1 from neutron diffraction data reveals that tin is preferentially located in the tetrahedral layers of the brownmillerite. Paper presented at the 11th EuroConference on the Science and Technology of Ionics, Batz-sur-Mer, Sept. 9–15, 2007  相似文献   

20.
Infrared (IR) absorption and luminescence in chemically and radiation-modified natural Armenian Zeolite (clinoptilolite) samples have been studied. The luminescence was studied in 390–450 nm and 620–710 nm wavelength bands, and the IR measurements were carried out in the 400–5400 cm−1 range. It is shown that the luminescence intensity depends on the content of pure clinoptilolite in the samples and, probably on the distribution of “passive” luminescence centers over Si and Al sites that became “active” under radiation or chemical treatment. The samples of electron irradiated clinoptilolite have higher luminescence intensity than the chemically and thermally treated ones. A decrease in the intensity of IR absorption bands at 3550 cm−1 and 3650 cm−1 was found after irradiation.  相似文献   

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