ESR spectroscopy of La2Ga5SiO14:Cr single crystals

The ESR spectrum of La₃Ga₅SiO₁₄ single crystals activated by chromium ions is investigated. It is shown that chromium ions are incorporated into the La₃Ga₅SiO₁₄ crystal lattice in the trivalent state at laoctahedric positions. Orientations of the principal magnetic axes are determined, and parameters of the spin Hamiltonian are estimated. The effect of disorder of the crystal structure of the matrix on line widths and shapes of the ESR spectrum of impurity Cr³⁺ ions is discussed. I. Franko L’vov State University, 50, Dragomilov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 6, pp. 942–946, November–December, 1998.     

Optical and EPR spectroscopy of manganese ions in Sr3Ga2Ge4O14 crystals

Results of investigations of the spectroscopic properties of manganese-activated single crystals of Sr₃Ga₂Ge₄O₁₄ by the methods of optical and EPR spectroscopy are reported. It is shown that magnagese activator ions form substitutional centers Mn³⁺ and Mn²⁺ in 1a-octahedral positions of the Sr₃Ga₂Ge₄O₁₄ lattice. Changes in the opticla properties of Sr₃Ga₂Ge₄O₁₄: Mn after vacuum thermal annealing are attributed to charge transfer of some of the manganese ions (Mn³⁺→Mn²⁺). The relationship between the spectroscopical properties of Mn²⁺ ions and the crystallochemical structure of the system are discussed. I. Franko L’vov State University, 50, Dragomanov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 779–783, November–December, 1997.     

The absorption spectrum of radiation-colored SrCl2-Ce crystals

We investigate the spectra of the x-ray radiation-induced absorption of SrCl₂−Ce crystals over the spectral range 345–830 nm and their temperature transformations in the interval from 77 to 450 K. We found that radiative color centers are characterized by a complex spectrum of induced absorption that contains wide bands of photochromic PC (750, 519, 378 nm) and PC⁺ (620, 446, 340 nm) centers and quasi-linear bands of Ce²⁺ centers. The most significant thermal transformations of radiative color centers occur in the vicinity of the thermostimulated luminescence peak of 394 K, at which the holes of the PC⁺ centers recombine with the electrons of the Ce²⁺ centers. Ivan Franko L’vov State University, 8, Kirilla i Mefodiya St., L’vov 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 545–547, July–August, 1997.     

Vibrational spectra of thin films of lead and bismuth tungstates

The IR reflection spectra are investigated for the systems “thin film of PbWO₄ or Bi₂WO₆-molten quartz v-SiO₂ substrate” within the region of 400–1600 cm⁻¹ at T=295 K. Interference in the thin films is considered. Interpretation of the bands belonging to the PbWO₄ and Bi₂WO₆ films is carried out. I. Franko L’vov State University, 50, Dragomanova St., 290005, L’vov, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 459–461, May–June, 1998.     

Luminescence centers in Sc2O3

Sc₂O₃ luminescence spectra are studied. The spectra are separated into elementary bands by the Alentsev–Fock method. It is established that the luminescence spectra consist of a number of overlapping bands with maxima at 3.5; 3.05; 2.65; 2.35, and 2.05 eV. The band at 3.5 eV is interpreted as emission of self-localized excitons, and the other bands, as defect-center recombination. L’vov State University, 50, Dragomanov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 776–778, November–December, 1997.     

Optical properties of the proton conductor (NH2(CH3)2)2CoCl4

Based on the data from optical-spectral studies of (NH₂(CH₃)₂)₂CoCl₄ crystals, the existence of high-temperature phase transitions at 419, 380, 352, and 313 K is confirmed. It was shown that with the exception of the first transition, they are related to a considerable extent to rearrangement of the network of hydrogen bonds and are not accompanied by, considerable deformation of the lattice. In this connection the character of the electron-phonon interaction remains unchanged in the entire temperature range of the measurements. The (NH₂(CH₃)₂)₂CoCl₄ structure at room temperature is close to that of the ordered low-temperature phases of such isomorphous crystals as β-K₂SO₄. I. Franko State University, L’vov, Ukraine, 8, Kirill and Mefodii St., UA-290005, L’vov. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 412–418, May–June, 1998.     

Luminescence centers in yttrium silicate and germanate

Luminescence spectra for isostructural Y₂SiO₅ and Y₂GeO₅ are investigated. The spectra are resolved into elementary components by the Alentsev—Fock method. Bands with maxima in regions of 2.6, 2.3, and 2.05 eV in the spectra of Y₂SiO₅ luminescence and in regions of 2.55, 2.25, and 2.0 eV in the spectra of Y₂GeO₅ luminescence are considered as radiative recombination of excited associative donor-acceptor Y³⁺−O²⁻ pairs. The indicated bands are related to certain distances between yttrium (the donor) and oxygen (the acceptor). A band with a maximum of 2.95 eV in Y₂SiO₅ and 3.0 eV in Y₂GeO₅ occurs in recombination of electrons with holes trapped by an anionic sublattice. I. Franko L’vov State University, 50, Dragomanov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 4, pp. 528–531, July–August, 1998.     

Luminescence centers in thin films of lead and bismuth tungstates

Luminescence spectra of thin films of PbWO₄ and Bi₂WO₆ are invesigated. The Alentsev-Fock method is used to separate the spectra into elementary components. The emission bands with maxima at 2.8 eV in PbWO₄ and at 2.93 eV in Bi₂WO₆ luminescence spectra are interpreted as the emission of self-localized Frenkel excitons. The bands with maxima at 2.35 and 1.75 eV in PbWO₄ and at 2.35 and 1.9 eV in Bi₂WO₆ are related to oxygen vacancies. L’vov State University, 50, Dragomanov St., L'vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp. 143–145, January–February, 1998.     

A Generalization of Scaling Models of Turbulence

We report on some implications of the theory of turbulence developed by V. Yakhot (Phys. Rev. E 57(2):1737, 1998). In particular we focus on the expression for the scaling exponents ζ _n . We show that Yakhot’s result contains three well known scaling models as special cases, namely K41, K62 and the theory by V. L’vov and I. Procaccia (Phys. Rev. E 62(6):8037, 2000). The model furthermore yields a theoretical justification for the method of extended self-similarity (ESS).     

Luminescence of mercurylike impurities in single-crystal CdWO4 compounds

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 (V_Cd-WO₆) with hv_max=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 hv_max=2.87 eV, while in luminescence of CdWO4, radiation of centers (BiO₆) with hv_max=2.16 eV and of complexes (V_Cd-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.     

Stress-Induced Alteration of Chlorophyll Fluorescence Polarization and Spectrum in Leaves of <Emphasis Type="Italic">Alocasia macrorrhiza</Emphasis> L. Schott

The value of intrinsic chlorophyll fluorescence polarization, and the intensity in emission spectrum were investigated in leaf segments of Alocasia macrorrhiza under several stress conditions including different temperatures (25–50°C), various concentrations of NaCl (0–250 mM), methyl viologen (MV, 0–25 μM), SDS (0–1.0%) and NaHSO₃ (0–80 μM). Fluorescence emission spectrum of leaves at wavelength regions of 500–800 nm was monitored by excitation at 436 nm. The value of fluorescence polarization (P value), as result of energy transfer and mutual orientation between chlorophyll molecules, was determined by excitation at 436 nm and emission at 685 nm. The results showed that elevated temperature and concentrations of salt (NaCl), photooxidant (MV), surfactant (SDS) and simulated SO₂ (NaHSO₃) treatments all induced a reduction of fluorescence polarization to various degrees. However, alteration of the fluorescence spectrum and emission intensity of F₆₈₅ and F₇₃₁ depended on the individual treatment. Increase in temperature and concentration of NaHSO₃ enhanced fluorescence intensity mainly at F₆₈₅, while an increase in MV concentration led to a decrease at both F₆₈₅ and F₇₃₁. On the contrary, NaCl and SDS did not cause remarkable change in fluorescence spectrum. Among different treatments, the negative correlation between polarization and fluorescence intensity was found with NaHSO₃ treatments only. We concluded that P value being measured with intrinsic chlorophyll fluorescence as probe in leaves is a susceptible indicator responding to changes in environmental conditions. The alteration of P value and fluorescence intensity might not always be shown a functional relation pattern. The possible reasons of differed response to various treatments were discussed.     

Comparison of the Seltzer Coefficient C 1 to Experimental Data

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.     

Effect of interface recombination of charge carriers on the photoconductivity of variable-band structures

The effect of interface recombination of charge carriers on photoconductivity of variable-band structures with extrinsic conductivity type and a linear coordinate dependence of the forbidden band width has been studied theoretically. It has been shown that under conditions of strong light absorption the interface recombination of charge carriers leads to the formation of a minimum, in the photoconduction spectrum for a photon energy equal to the forbidden band width at the interface. The details of the spectral dependence of the photoconductivity of a variable-band structure in the neighborhood of the photoconductivity minimum are analyzed. Institute of Applied Physics, Iv. Franko L’vov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 94–98, July, 1997.     

X-ray photoelectron spectroscopy study of the electronic structure of La<Subscript>1–<Emphasis Type="Italic">x</Emphasis></Subscript>Ca<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>MnO<Subscript>3+δ</Subscript> solid solutions

The electronic structure of La_1–x Ga _x MnO_3+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 Mn2p_3/2 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 Mn2p_3/2 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 La_1–x Ga _x MnO_3+δ. (0 ≤ x < 1) and the binding energy of the Mn2p_3/2 peak. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 419–427, May–June, 2009.     

Anomalous scattering factors of some rare earth elements evaluated using photon interaction cross-sections

The real and imaginary parts,f’(E) and”(E) of the dispersion corrections to the forward Rayleigh scattering amplitude (also called anomalous scattering factors) for the elements La, Ce, Pr, Nd, Sm, Gd, Dy, Ho and Er, have been determined by a numerical evaluation of the dispersion integral that relates them through the optical theorem to the photoeffect cross-sections. The photoeffect cross-sections are derived from the total attenuation cross-section data set experimentally determined using high resolution high purity germanium detector in a narrow beam good geometry set-up for these elements in the photon energy range 5 to 1332 keV and reported earlier by the authors. Below 5 keV, Scofield’s photoeffect cross-sections compiled in XCOM program have been interpolated and used. Simple formulae forf” in terms of atomic number and energy have also been obtained. The data cover the energy region from 6 to 85 keV and atomic numberZ from 57–68. The results obtained are found to agree fairly well with the other available data.     

Comment on “solution of the problem of catastrophic relaxation of homogeneous spin precession in superfluid 3He-B”

The argument of Bunkov, L’vov and Volovik contains errors, thus, making the result obtained nonconvincing. The text was submitted by the author in English.     

Transverse discharge with prebreakdown ionization multiplication of electrons in the working media of N2- and HF-lasers

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.     

Perturbative and non-perturbative Kolmogorov turbulence in a gluon plasma

In numerical simulations of nonabelian plasma instabilities in the hard-loop approximation, a turbulent spectrum has been observed that is characterized by a phase-space density of particles n(p)∼p ^−ν with exponent ν≃2, which is larger than expected from relativistic 2↔2 scatterings. Using the approach of Zakharov, L’vov and Falkovich, we analyze possible Kolmogorov coefficients for relativistic (m≥4)-particle processes, which give at most ν=5/3 perturbatively for an energy cascade. We discuss non-perturbative scenarios which lead to larger values. As an extreme limit we find the result ν=5 generically in an inherently non-perturbative effective field theory situation, which coincides with results obtained by Berges et al. in large-N scalar field theory. If we instead assume that scaling behavior is determined by Schwinger–Dyson resummations such that the different scaling of bare and dressed vertices matters, we find that intermediate values are possible. We present one simple scenario, which would single out ν=2.     

Spectral reflection characteristics of spruce needles and leaves of trees in the zones with industrially polluted air

We analyze the results of laboratory measurements for the reflection spectra of spruce needles and maple leaves from zones with different degrees of air pollution by SO₂ and NO_x oxides. The calculated first derivatives and vegation indices are discussed. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 789–792, November–December, 1997.     

WnNim(n+m=8)团簇的极性和光谱性质的理论研究

采用密度泛函理论(DFT)中的B3LYP方法,在LANL2DZ基组水平上对WnNim(n+m=8)团簇的各种可能构型进行了几何参数全优化,得到了它们的基态构型;并对基态构型的偶极距、极化率、红外光谱和拉曼光谱性质进行了分析,结果表明:团簇WnNim(n+m=8)都具有极性,富W团簇非线性光学效应强,容易被外加场极化;振动频率主要分布在0-350 cm-1范围内,团簇W4Ni4因其振动方式的特殊性,红外光谱和拉曼光谱在频率421.971 cm-1处,都有明显强峰;团簇W5Ni3因其结构的高对称性在振动光谱中出现多处共振现象.