The Phase Diagrams for 11 Binary Alkali Halide Systems Having Common Anion

The quasiregular model is improved. Using the thermodynamic condition of phase equilibrium we obtain the equations of solid-liquid phase equilibrium curves. The phase diagrams for 11 binary alkali halide systeme having common anion have been obtained. The eutectic point of each phase diagram ie also calculated. The results show that the agreement of theoretical curves with the experimental reeults ie good (except the system CsBr-NaBr).     

Self-Trapped Excitons in Ionic-Covalent Silver Halide Crystals and Nanostructures: High-Frequency EPR, ESE, ENDOR and ODMR Studies

Silver halides have unique features in solid state physics because their properties are considered to be of borderline nature between ionic and covalent bonding. In AgCl, the self-trapped hole (STH) is centered and partly trapped in the cationic sublattice, forming an Ag²⁺ ion inside of a (AgCl₆)^4? complex as a result of the Jahn–Teller distortion. The STH in AgCl can capture an electron from the conduction band forming the self-trapped exciton (STE). Recent results of a study of STE by means of high-frequency electron paramagnetic resonance, electron spin echo, electron–nuclear double resonance (ENDOR) and optically detected magnetic resonance (ODMR) are reviewed. The properties of the STE in AgCl crystals, such as exchange coupling, the ordering of the triplet and singlet sublevels, the dynamical properties of the singlet and triplet states, and the hyperfine interaction with the Ag and Cl (Br) nuclei are discussed. Direct information about the spatial distribution of the wave function of STE unpaired electrons was obtained by ENDOR. From a comparison with the results of an ENDOR study of the shallow electron center and STH, it is concluded that the electron is mainly contained in a hydrogen-like 1s orbital with a Bohr radius of 15.1 ± 0.6 Å, but near its center the electron density reflects the charge distribution of the hole. The hole of the STE is virtually identical to an isolated STH center. For AgCl nanocrystals embedded into the KCl crystalline matrix, the anisotropy of the g-factor of STE and STH was found to be substantially reduced compared with that of bulk AgCl crystals, which can be explained by a considerable suppression of the Jahn–Teller effect in nanoparticles. A study of ODMR in AgBr nanocrystals in KBr revealed spatial confinement effects and allowed estimating the nanocrystal size from the shape of the ODMR spectra.     

高压下碱卤晶体的三参量等温状态方程

 由等温体积弹性模量的定义及其与压强关系的假设出发,导出了一个新的适用于高压下碱卤晶体的三参量等温状态方程。计算了室温下NaCl晶体在0～30 GPa压强范围内、CsCl晶体在0～40 GPa压强范围内的相对体积以及NaCl晶体在0～30 GPa压强范围内的等温体积弹性模量,计算结果与实验值一致。对等温体积弹性模量及其对压强的一阶、二阶导数与压强的关系进行了讨论,指出压强趋于无穷大时的等温体积弹性模量是常数。     

Localization of Excitons on Planar Defects in Semiconductor Crystals

JETP Letters - Motivated by recent experimental and computational investigations of bilayer, hydrogenated and fluorinated graphene, we apply the formalisms of U(1) quantum electrodynamics and SU(2)...     

Quantitative Determination of Reactive Species in Alkali Halide Disks

Abstract

As part of an infrared investigation of the kinetics of the reactions of KMnO₄ in a KI disk and of KIO₄ in a KI disk, the stoichiometry of the two reactions was needed. A previous study¹ has shown that MnO₄ ^? reacts in a KI matrix to produce IO₄ ^? (which then reacts further to form IO₃ ^?) and MnO₂. Iodate ion is the only observable product in the reaction of IO₄ ^? in a KI matrix¹. The infrared absorption at 740cm^?1, which is due to the presence of IO₃ ^?, was found to obey the Beer-Lambert Law. However, calibration curves for KMnO₄ in KI and for KIO₄ in KI could not be obtained because both species reacted with the dispersing medium during the preparation of the disk¹. It was also observed that no immediate reaction occurred when KBr or KC1 disks containing KMnO₄, or KIO₄ were prepared. Thus, an extrapolation method was sought which would permit the estimation of calibration curves for the reactive species.     

On Optical Sensing of Alkali Halide Crystal Surfaces

The surface quality of alkali halide crystals to be used in spectroscopy and as laser components has been sensed using a computer-generated hologram together with digital image processing. FFT and two-dimensional cross-correlation analyses. Surfaces cleaved only or finished to various extents are considered as examples.     

Influence of Cation Impurities and Both Cation and Anion Nonstoichiometry on Aluminum Oxide Energy Gap Width

JETP Letters - Using the coherent potential approximation, the electronic structure of α- $${\text{A}}{{{\text{l}}}_{2}}{{{\text{O}}}_{3}}$$ (corundum) with various concentrations of mono and...     

Growing of Alkaline Earth Halide Scintillation Crystals and Their Optical Properties

Physics of the Solid State - The features of using the Bridgman method for growing alkaline earth halides crystals BaBrI, BaClI, and SrBrI are discussed. The results of the study of scintillation...     

钙钛矿晶体的电荷复合动力学研究

本文利用紫外吸收光谱和稳态荧光光谱技术结合理论模型,研究了钙钛矿材料CH₃NH₃PbI₃晶体在光激发过程中的电荷复合动力学行为,进而获得晶体的扩散长度. 电荷载体的扩散长度是判断光电材料的重要参数. 研究通过合成两种不同缺陷态浓度的CH₃NH₃PbI₃晶体,测量这两种晶体在0.019∽4.268 μJ/cm²的激光激发下的时间分辨荧光光谱,利用动力学模型对光谱进行拟合,可以获得每个晶体的掺杂浓度,空穴浓度以及电荷复合参数. 将这些参数结合已有公式,最终可获得每个晶体的电荷载体的扩散长度.     

Crystal Size Effects in the Raman Spectra of Orthorhombic Hydrogen Halide Crystals

The Raman spectra of the stretching regions of the orthorhombic forms of hydrogen chloride and hydrogen bromide are found to depend on the method of crystal growth. The significance of this in connection with the interpretation of crystallographic and spectroscopic data is discussed.     

The Role of Oxygen Containing Impurities in Defects Formation in Cesium Halide Crystals

The dependence of defect formation efficiency in CsI single crystals both on the type of oxygen containing impurities and the value of the absorbed irradiation dose was studied. Correlative results were obtained under investigation by methods of ionic thermocurrent (ITC), thermostimulated exoemission (TSEE), electrical conductivity and optical spectroscopy. The peculiarities of defect formation in γ-irradiated CsI-CO₃(SO₄, OH) and X-irradiated CsI-OH single crystals are discussed.     

Excitons in PL Spectra of Cu(In,Ga)Se2 Single Crystals

Physics of the Solid State - A photoluminescence (PL) study of Cu(In,Ga)Se2 (CIGSe) single crystals, (grown by the vertical Bridgman technique) with the [Ga]/[Ga + In] ratio of 7 and 12% and the...     

正、负电性纳米银吸附阴、阳离子型分子的SERS比较

使用表面带负电的胶态纳米银,分别进行阴,阳离子型分子的SERS效应研究,并与表面带正电的胶态纳米银比较,当阳离子型分子盐酸副玫瑰苯胺吸附在正,负电性纳米银表面上时,后者SERS较强,当阴离子型分子吲哚丁酸分别吸附在这两种胶态纳米银上时,后者无SERS效应。     

钒氧卟啉正负离子的结构畸变与电子-振动耦合的DFT研究

用PBE1PBE方法研究了钒氧卟啉一价阴离子([VOP]^-)、一价阳离子([VOP]⁺)的单态和三重态结构. 结果表明[VOP]^-和[VOP]⁺的最稳定电子态均为三重态,其未配对电子一个占据钒的d_xy轨道,另一个占据卟啉环的π轨道,因此两者均为π-自由基. 中性分子(VOP)的双重态最稳定,其未配对电子占据钒的d_xy轨道. 双重态VOP具有较高的C_4v对称性,而三重态[VOP]^- 离子由于发生姜-泰勒效应对称性降低为C_2v. 计算了[VOP]^-姜-泰勒活性振动模式的电子-振动耦合常数,并用前线KS轨道的节面分布解释了姜-泰勒畸变沿特定简正模式发生的原因. 三重态[VOP]⁺ 阳离子的卟啉环发生键长交替变化,构型畸变起源于电子态近简并引起的赝姜-泰勒效应,导致其对称性从C_4v降低为C₄,其结构变化可以用重组的前线KS轨道的节面分布解释.     

Non-Markoffian Dynamic Evolution of Spontaneous Emission in Photonic Crystals

The spontaneous emission of a two level atom embedded in photonic crystals is investigated. The photonic crystal will lead to the feedback of the atom-emitted radiation which will influence the evolution of the atom. Because the feedback is within the time scale of a few optical periods, the Markoffian approximation could not be applied for the study of the time evolution of the atom. Due to the feedback of the reflected waves at different interfaces of the photonic crystals, the atomic evolution is quite different from the vacuum.     

LiS分子和离子基态的精确理论研究

Potential energies of LiS(²Π), LiS^-(¹Σ⁺) and LiS⁺(³Σ^-) are calculated by using the multireference configuration interaction method including Davidson correction and the augmented correlation-consistent basis sets aug-cc-PV(X+d)Z (X=T, Q). Such obtained potential energies are subsequently extrapolated to the complete basis set limit. Both the core-valence correction and the relativistic effect are also considered. The analytical potential energy functions are then obtained by fitting such accurate energies utilizing a least-squares fitting procedure. By using such analytical potential energy functions, we obtain the accurate spectroscopic parameters, complete set of vibrational levels and classical turning points. The present results are compared well with the experimental and other theoretical work.     

Theoretical Calculation of the Eutectic Point for 27 Binary Alkali Halide Systems Having Common Ions

We suppose that the excess enthalpy and entropy may be expanded as polynomials in the mole fractions, and determine the equations of the liquid-solid phase equilibrium curves of a binary system according to thermodynamic theory. For the 27 binary alkali halide systems having the phase diagram with an eutectic point, we calculate the values of the eutectic point (T_o, X_Bo). These results agree well with the experimental values.     

Generating Tunable Magnetism in AlN Nanoribbons Using Anion/Cation Vacancies:a First-Principles Prediction

Using first-principles approach, we theoretically study the effect of anion/cation vacancies on structural and electro-magnetic properties of zigzag AlN nanoribbons (ZAlNNRs). Calculations were performed using a full spin-polarized method within the density functional theory (DFT). Our findings shed light on how the edge states combined with vacancy engineering can affect electro-magnetic properties of ZAlNNRs. We found that depending on the nature and number of vacancies, ZAlNNRs can design as half-metal or semiconductor. Our results reveal a significant amount of spin magnetic moment for ZAlNNR with Al vacancies (V_Al). These results may open new applications of AlN nano-materials in spintronics.     

Low－Temperature Spectral Properties and Zero－Phonon Transitions of Alkali Halide Crystal Materials Bombarded with Electrons and Implanted with Ions

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