Model for milling of powders

A model is proposed for mechanical milling of powders that relates the applied energy to average particle size D in the powders. It is shown that the milling energy is consumed for the rupture of interatomic bonds in crystalline particles and for the creation of an additional surface during powder fragmentation. The appearance of microstrains ɛ retards powder fragmentation. Average particle size D after milling decreases with increasing milling time t and decreasing particle size in the initial powder or its mass M. The calculated results are compared to the experimental data obtained on a tungsten carbide WC powder.     

Influence of carrier cations on the intensity of spectral lines of microelements in atomic-emission spectral analysis

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 1, pp. 18–21, January, 1991.     

Physical features of the spectral distribution of circularly polarized synchrotron radiation intensity

An asymptotic formula is constructed for the dependence of the serial number of harmonic on the relativistic factor for circularly polarized synchrotron radiation in the upper half-plane. Numerical values of particle velocities at which the maximum of synchrotron radiation intensity is transferred from one harmonic to another are obtained.     

Influence of structural parameters on electroluminescent emittance

On the basis of the measurements made in [1], [2], [3], [4], [5], [6] and [7], and from the relation derived by Goldberg [8] and empirically improved in [6] and [7], a new relation is derived for the dependence of the electroluminescent emittance on the structural parameters of electroluminescent material. The relation, which is in qualitative agreement with the experimentally obtained dependence of electroluminescent emittance, leads to conclusions for improving the preparation of electroluminescent powders and layers.     

Organic electroluminescent devices and their application

Several organic electroluminescent devices have been fabricated by multi-source high vacuum deposition system. For high brightness organic electroluminescent device, the maximum brightness is over 40000 cd/m². For quantum well structures, quantum size effect has been investigated and the high light emission efficiencies of the devices have been obtained. White-light emission from organic multi-quantum well structures is proposed at first. Brightness of the white-light MQW devices reaches 4000 cd/m² at 17 V. Presented at the 1st Czech-Chinese Workshop “Advanced Materials for Optoelectronics”, Prague, Czech Republic, June 13–17, 1998. The research is supported by the National “863” Project of China [No. 863-307-05-05(02)] and by the National Natural Science Foundation of China [No. 69637010].     

An integral equation for the average radiation intensity in a stochastically macroinhomogeneous

An integral equation for the average intensity is derived for a simplified model of a stochastic macroinhomogeneous medium in the form of a stochastic field of attenuation and scattering co-efficients. This equation can be solved by the Monte Carlo method. A simulation algorithm is developed, maximally approximating the well-known algorithm for a deterministic medium. As an example, the algorithm is used to calculate the flux of solar radiation transmitted through a cloud layer.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 103–107, September, 1977.The authors are indebted to G. A. Mikhailov for a discussion and valuable comments as well as to G. M. Krekov for general interest and consultation.     

Influence of chaotic pump radiation with finite bandwidth on the intensity correlation of resonance fluorescence radiation

It is shown that the bandwidth of chaotic pump radiation can strongly influence the behavior of the intensity correlation of resonance fluorescence in contrast to a laser pump. This different behavior arises from the different higher order coherence properties of chaotic and laser light with the same bandwidth.     

Influence of terahertz laser radiation on the spectral characteristics and functional properties of albumin

The exposure of albumin (transport protein of blood serum) to laser radiation with a frequency of 3.6 THz resulted in a change in the intensity of characteristic bands in UV absorption spectra and in circular dichroism spectra. These changes depend on the exposure duration and the laser radiation power and indicate conformational changes in protein molecules.     

Quark-antiquark states and their radiative transitions in terms of the spectral integral equation: Charmonia

Earlier by the authors (Yad. Fiz. 70, 68 (2007)), the bƃ states were treated in the framework of the spectral integral equation, together with simultaneous calculations of radiative decays of the considered bottomonia. In the present paper, such a study is carried out for the charmonium states. We reconstruct the interaction in the c-c sector on the basis of the data for the charmonium levels with J _PC = 0⁻⁺, 1⁻⁻, 0⁺⁺, 1⁺⁺, 2⁺⁺, 1⁺⁻ and radiative transitions ψ(2S) → γχ _c0(1P), γχ _c1(1P), γχ _c2(1P), γχ _c(1S) and χ _c0(1P), χ _c1(1P), χ _c2(1P) → γJ/ψ. The c-c levels and their wave functions are calculated for the radial excitations with n ≤ 6. Also, we determine the c-c component of the photon wave function using the e ⁺ e ⁻-annihilation data: e ⁺ e ⁻ → J/ψ(3097), ψ(3686), ψ(3770), ψ(4040), ψ(4160), ψ(4415) and perform the calculations of the partial widths of the two-photon decays for the n = 1 states η _c0(1S), χ _c0(1P), χ _c2(1P) → γγ and n = 2 states η _c0(2S) → γγ, χ _c0(2P) → γγ. We discuss the status of the recently observed c-c states X(3872) and Y(3941): according to our results, the X(3872) can be either χ _c1(2P) or η _c2(1D), while Y(3941) is χ _c2(2P). The text was submitted by the authors in English.     

Quark-Antiquark states and their radiative transitions in terms of the spectral integral equation: Bottomonia

In the framework of the spectral integral equation, we consider the states and their radiative transitions. We reconstruct the interaction on the basis of data for the levels of the bottomonium states with J ^PC = 0⁻⁺, 1⁻⁻, 0⁺⁺, 1⁺⁺, 2⁺⁺ as well as the data for the radiative transitions γ (3S) → _γχbJ(2P) and γ(2S) → _γχbJ(1P) with J = 0, 1, 2. We calculate bottomonium levels with the radial quantum numbers n ≤ 6, their wave functions, and corresponding radiative transitions. The ratios Br[_χbJ(2P) → _γγ(2S)]/Br[_χbJ(2P) → _γγ(1S)] for J = 0, 1, 2 are found to be in agreement with data. We determine the component of the photon wave function using the data for the e ⁺ e ⁻ annihilation, e ⁺ e ⁻ → γ(9460), γ(10 023), γ(10 036), γ(10 580), γ(10 865), γ(11 019), and predict partial widths of the two-photon decays ηb0 → γγ, χb0 → γγ, χb2 → γγ for the radial excitation states below the threshold (n ≤ 3). The text was submitted by the authors in English.     

Characterization of nanocrystalline FeSiCr powders prepared by ball milling

FeSi₁₀Cr₁₀ powder was mechanically alloyed by high energy planetary ball milling, starting from elemental powders. The microstructural and magnetic properties of the milled powders were characterized by scanning electron microscopy, X-ray diffraction, ⁵⁷Fe Mössbauer spectrometry and a vibratory sample magnetometer.After 3 h of milling, the formation of two bcc solid solutions α-Fe₁ (Si, Cr) and α-Fe₂ (Si, Cr) is observed. Their grain sizes decrease with increase in milling time attaining, at 15 h of milling, 23 and 11 nm, respectively. Mössbauer spectra of the milled powder show the presence of two components. One is a ferromagnetic type with a broad sextuplet. Its distribution of hyperfine field is characterized by high and low hyperfine field’s peaks and a mean value of 26.5 T. The other is a single paramagnetic peak. Its low concentration increases to ∼4% at 15 h of milling. These results can be explained by different atomic environments affected by Si or/and Cr elements, as well as the increased disordered grain boundaries.Magnetic measurements of the milled FeSi₁₀Cr₁₀ alloy powder exhibit a soft ferromagnetic character with a decrease of both magnetization at saturation (Ms) and coercive force (Hc) with milling time attaining values of Ms=151 emu/g and Hc=2500 A/m at 30 h of milling time.