Comparison of luminescence characteristics of Doped Molecular crystals grown by various methods

The effect of growth conditions on the line broadening in low temperature luminescence spectra of pyrene-doped biphenyl single crystals in investigated. It has been shown that the crystals, grown by plate sublimation technique, possess the minimal linewidth. Various possible mechanisms of line broadening are discussed.     

Thermodynamic study of some solid solutions in the CaOZrO2 system by emf method

The thermodynamic properties of some solid solutions in the CaOZrO₂ system have been investigated by using solid electrolyte galvanic cells of the type: O₂, Pt|CaO, CaF₂|CaF₂ (t_F = 1)| δCaO(1 ? δ)ZrO₂, CaF₂|Pt, O₂. The influence of CaF₂ added in electrodes on the thermodynamic equilibrium was investigated. It was shown that the heterogeneous field with cubic solid solution reaches the composition x = 0.17 mole of CaO. The results indicate that addition of ZrO₂ to the saturated solid solution produces a significant decrease in the activity of CaO. Measured data were used to calculate thermodynamic parameters of reactions with saturated solid solutions Ca_0.17 Zr_0.83 O_1.83, ZrO₂, and CaZrO₃. At temperatures below 820°C, saturated solid solutions have a tendency to decompose into CaZrO₃ and ZrO₂. A comparison of the thermodynamic results with available data on phase relationships in the CaOZrO₂ system is presented. High thermodynamic stability of SrZrO₃ and BaZrO₃ is one of the reasons for the absence of cubic solid solutions in the system MeOZrO₂ (MeSr, Ba).     

Higher order symmetrizer and application to an unusual transport equation

We study a class of stationary transport equation with nonlocal low-order tems We obtain the existence and uniqueness of a solution in sobolev spaces     

求解复杂湍流的非线性涡黏性系数模型和代数应力模型

非线性涡黏性系数模型和代数应力模型联系了线性涡黏性系数湍流模型和完整的微分 雷诺应力模型.随着它们受到日益关注,其形式也越来越多样化.本篇综述的目的是对这些模 型加以总结并比较它们之间的共同点及不同之处,指出它们与完整微分雷诺应力模型之间的 关系,以及相对于线性涡黏性系数模型而言它们在预报流场上所具有的优势.     

Multiphoton avalanche generation of free carriers in a multiband crystal

A new mechanism for generating nonequilibrium electron-hole pairs in transparent wide-gap crystals under high-power picosecond light pulses of prebreakdown intensity is considered. The kinetics of free carrier generation is investigated by the numerical solution of the system of balance equations for particle concentrations within the multiband model of electron energy spectrum of the crystal. It is shown that in the intensity range of 10¹⁰–10¹² W/cm² the proposed way of nonequilibrium carrier generation is more effective in the case of picosecond pulses than the conventional multiphoton absorption. It is shown that the nonequilibrium carrier generation considered here may initiate a multiphoton avalanche.     

Interband phototransitions in AgBr nanocrystals assisted by free carriers

The photolysis of AgBr nanocrystals irradiated by picosecond light pulses with quantum energies of 3.51 and 1.17 eV is theoretically analyzed. The observed dependences of the photometric density on the long-wavelength radiation intensity are shown to be determined by the photogeneration of nonequilibrium electron-hole pairs as a result of indirect interband phototransitions involving free electrons. For such electrons to be involved in this process, they should possess a high kinetic energy, which is acquired due to intraband non-linear absorption of the intense long-wavelength radiation.     

Thermodynamics of double oxides I. Galvanic-cell study of strontium tungstates and aluminates

Electrochemical cells employing La₂O₃ and CaO doped thoria and CaF₂ as solid electrolytes were used to determine the standard Gibbs energies of formation of some tungstates and aluminates of strontium in the range of 1100 to 1400 K. Enthalpies of formation and entropies of Sr₃WO₆, Sr₂WO₅, SrWO₄, Sr₃Al₂O₆ and SrAl₂O₄ have been calculated. Concordance of the results from cells with different combinations of electrodes confirms the reliability of the thermodynamic results.     

Ionization of deep quantum wells: Optical trampoline effect

A new mechanism of transitions of an electronic system from the ground state to states with excitation energies exceeding many times the energy of a light photon initiating the transitions has been considered. This mechanism is based on the so-called optical “trampoline” effect: one of the interacting electrons receives energy from another electron and, simultaneously absorbing a photon ?ω, overcomes the energy gap significantly exceeding ?ω. Ionization of deep quantum wells by low-frequency light of moderate intensity due to the optical trampoline effect was calculated.     

Systematics of exclusive diffraction dissociation modes inK ± p interactions at 32 GeV/c

We present results of an investigation of diffraction dissociation in exclusive channels inK ^± p interactions at 32 GeV/c. Total cross sections are determined forK ^±→K ^±π⁺π^?,K ^±2π⁺2π^?,K ⁰π^±π^± K ^±2π⁺π^?,K ^± K ⁺ K ^?,K ^±p \(\bar p\) , \(\bar \Lambda \) p, andp→pπ ⁺π^?,p2π⁺2π^?,pK ⁺K^?,ΛK ⁺,ΛK ⁺π⁺π^? dissociation modes, ranging from a high of ? 300 μb to ～ 3 μb. Thedσ/dt′ differential cross sections of most of the systems studied exhibit structure, with breaks of slope att′ ～ 0.2 to 0.5 GeV²; some modes have a sharp forward spike with a slope exceeding 10 GeV^?2. A systematic investigation of two-body dissociation modesK→A+B andp→A′+B′ shows that these cross sections decrease with increasing threshold massM _A+M _B, that they are comparable for kaon and proton dissociations at similar diffractive excitation masses and are systematically suppressed by a factor 3–4 for dissociations requiring an \(s\bar s\) quark pair creation when compared to \(u\bar u\) pair creation indicating a breakdown ofSU ₃ symmetry for the \(q\bar q\) sea.