环形电极单间隙电晕放电伏安特性

基于用于直线变压器型驱动源的多间隙气体开关结构,提出一种环形放电间隙与电晕针并联的气体火花间隙。通过测量间隙耐压过程中电晕放电的伏安特性,研究了气体介质、气压、电晕极性、电晕针长度以及针尖对应电极结构等因素对伏安特性的影响。结果表明：以空气为绝缘气体,负极性电晕可获得较稳定的伏安特性;改变电晕针长度和针尖对应电极结构可方便地实现对电晕放电伏安特性的调节以满足开关要求。     

电离度效应对高电离态类氢离子平均寿命的影响

利用类氢离子新势函数模型,研究了电离度效应对高电离态类氢离子平均寿命的影响,计算了类氢Kr+35离子2p-8p态的平均寿命.发现电离度效应使类氢O+7-Pm+60离子各态的平均寿命相对减少0.26%～9.41%.结果对估价高电离态原子光谱和寿命的测量值有一定影响,有利于识别离子状态.     

The loop average for a baryon in the large-N limit

The Schwinger-Dyson equation for the Wilson loop is derived for a baryon. The obtained equation is shown to yield the planar diagrams in the large-N limit.     

Spin-lattice relaxation of the Vk-center in LiF

The angular and temperature dependences of the spin-lattice relaxation (SLR) rate of V_k-centers in LiF doped with Mg or Ag have been investigated. In the temperature interval 4.2–100 K the results can be fitted by the formula $\text{τ}{}^{\mathrm{?1}}\text{= A(θ)T + Be}{}^{\mathrm{<mtext>?\Delta </mtext><mtext>T</mtext>}}$ with A(0°) = 0.11 sec^?1K^?1, A(90°) = 1.3 sec^?1K^?1, B = 3 × 10⁵sec^?1 and Δ = (175 ± 15)K.A mechanism for the SLR is considered, assuming the modulation of the hyperfine interaction by phononinduced transitions between the ground and excited states of the resonant molecular vibrations of the V_k-center. This mechanism is found to explain the value, the temperature dependence and the isotropy of τ^?1 in the interval T = 20–100 K.The one-phonon SLR mechanisms of the V_k-center in the T < 10 K region are discussed.     

Distribution of valence quarks in hadrons at small x in QCD

Valence u- and d-quark distributions in nucleons and pions at small x corresponding to ? and ω Regge pole exchanges have been obtained on the basis of the QCD sum rule method.     

Structural,electronic and magnetic properties of the linear chain compounds CsMI3 (M = V, Cr, Mn) from 129I mössbauer spectroscopy

The crystal structures of the compounds CsVI₃ and CsMnI₃ belong to the space group P6₃/mmc. CsCrI₃ undergoes at 165 K a crystal phase transition from a hexagonal to an orthorhombic structure. The three-dimensional magnetic structure of CsMnI₃ consists of an arrangement of Mn moments parallel to the hexagonal c-axis and coupled antiferromagnetically within the chain. The electronic charge and spin densities in the iodine valence orbitals are deduced from an analysis of the hyperfine interaction parameters measured at the ¹²⁹I nucleus in CsVI₃, CsMnI₃ and CsCrI₃     

ESR of Vk centers in CsI

V_k centers (self trapped hole I^?₂) have been obtained in CsI doped with Tl⁺ or Na⁺ by X-irradiation at low temperature and studied by ESR. Spin-Hamiltonian parameters are calculated and compared with those obtained for I^?₂ in the other alkali iodides, as well as the energy of the forbidden transition ²Σ⁺_u→²Π_u and the s and p components of the fundamental state.     

Optically detected magnetic resonance of the V- centre in ZnSe

Optically detected magnetic resonance of V^- centres and donors has been observed in ZnSe. The spectral dependence of these resonances show that they are both associated with an emission band at 632 nm.     

X-ray photoemission spectra of valence electrons in V3X and Nb3X compounds

The X-ray photoemission spectra (XPS) of the A15 type compounds V₃Au, Nb₃Os, Nb₃Ir, Nb₃Pt and Nb₃Au have been studied. The inner level binding energies of the different components and the valence electron distribution were measured. The Nb4d and the X5d energy bands of the Nb₃X compounds appear to be more and more separate with increasing atomic number of the X component. The comparison between the results from X-ray emission spectroscopy (XES) and X-ray photoelectron spectroscopy (XPS) of corresponding V₃X and Nb₃X compounds points out the similarity of their electronic structures.     

平均价电子数与掺杂铁基砷化物超导电性关系

文中提出一个计算掺杂铁基砷化物平均价电子数的方法,研究了掺杂铁基砷化物平均价电子数Zv 和转变温度Tc之间的关系,发现他们之间有一定的规律性,由此,提出用平均价电子数作为提高掺杂铁基砷化物超导电性的一个新依据.     

On the path integral for the potential V = ar−2 + br2

A simple, alternative path integral formulation for the potential V = ar^?2 + br², r ? 0, is presented. This is achieved by mapping the problem to a two-dimensional oscillator and using the method of image paths.     

Electron energy loss spectra of the silicon 2p, 2s, carbon 1s and valence shells of tetramethylsilane

Inner shell excitation spectra of tetramethylsilane, (CH₃)₄Si, have been measured in the silicon 2s, 2p (L_I,II,III-shell) and carbon is (K-shell) regions using electron energy-loss spectroscopy at an impact energy of 2.5 keV and a scattering angle of ~1°. The high-resolution valence shell spectrum has also been observed at an impact energy of 3 keV and a zero degree scattering angle. The silicon 2p spectra are compared and contrasted with published photoabsorption spectra of SiF₄, SiH₄, and other related Si-containing molecules with varying ligands.     

价电子能量/能级拓扑指数与MgB2体系超导电性的关系

构建了价电子平均能量/能级拓扑指数mV,计算了二硼化镁体系及掺杂二硼化镁体系的0阶拓扑指数0V,发现与超导转变温度TC之间有良好的规律性,因此文中提出以电性连接性指数0V作为掺杂二硼化镁体系超导电性的判据。     

ESR and photoacoustic spectra of V2O5−MO2 (M = Se, Te, Ge) glasses

ESR spectra of V₂O₅?MO₂ (M = Ge, Se, Te) glasses are investigated in the range 298–498 K. The spectra at 298 K are characteristic of V⁴⁺ with the 3d¹ electron localized on a single ${}^{51}\text{V}\text{(I =}\text{7}\text{2}$) in the glass network. At higher temperature, the hyperfine structure progressively broadens, leading eventually to a broad, single ESR peak. These results are consistent with thermally-induced electron hopping from V⁴⁺ to V⁵⁺. Photoacoustic spectra of the glass at 298 K are characteristic of V⁴⁺ in a distorted octa environment. A correlation of ESR and PAS data suggests that covalency increased as M is charged from Ge through Te to Se.     

Measuring the dielectric constant of materials from valence EELS

Valence EELS combined with STEM provides an approach to determine the dielectric constant of materials in the optical range of frequencies. The paper describes the experimental procedure and discusses the critical aspects of valence electron energy-loss spectroscopy (VEELS) treatment. In particular, the relativistic losses might affect strongly the results, and therefore they have to be subtracted from the spectra prior the analysis. The normalization of the energy-loss function is performed assuming an uniform thickness of the investigated area, which is reasonably fulfilled for carefully prepared FIB samples. This procedure requires the presence of at least one reference material with known dielectric properties to determine the absolute thickness. Examples of measuring the dielectric constant for several materials and structures are presented.     

Study of Vκ centers in CsI crystal

V_κ centers have been observed in CsI doped with Na⁺ and Tl⁺ after X-ray irradiation at LHeT using optical and EPR techniques. It is shown that they are oriented along [100] directions. By studying thermoluminescence two types of thermal migration have been found, one due to linear displacement of the centers along the cubic axis and the other due to 90° rotations. They correspond to two glow peaks at 60 and 90° K respectively.     

低原子序数材料窄带多层膜的研制

为研制极紫外波段窄带多层膜反射镜,采用低原子序数材料组合设计了30.4 nm波长处Mg/SiC,Si/SiC,Si/B4C和Si/C多层膜反射镜,并与极紫外波段传统的Mo/Si多层膜反射镜进行对比。采用直流磁控溅射技术制备了这些多层膜,在国家同步辐射实验室辐射与计量光束线完成了多层膜反射率测量,测量结果表明：Mg/SiC多层膜的带宽最小,为1.44 nm,且反射率最高,为44%;而Mo/Si多层膜的反射率仅为24%,带宽为3.11 nm。实验结果证明了采用低原子序数材料组成的多层膜的带宽要比常规多层膜窄,该方法可以应用于极紫外波段高分辨研究。     

Calculation of the bond ionicity in complex oxides

A technique for calculating the bond ionicity of crystalline materials using electronegativities of elements and taking into account the structure of polyhedra of the complex-oxide structure is proposed.     

Composite structure of the V1 band in strongly sodium-doped KBr

A detailed analysis was made of the thermal annealing of V₁ band in strongly Na-doped KBr crystal. It was found that two components (406 and 415 nm) exist in V₁ band region in such crystals. The 415 nm component, which increases with a decrease of the 406 nm component and shows a 〈110〉 type dichroism, has been assigned to be H_AA and/or H_A'A band.     

平均价电子数与掺杂Y_1Ba_2Cu_3O_(7-δ)体系超导电性的关系

文中尝试引进平均价电子数对掺杂Y1Ba2Cu3O7-δ(YBCO)体系超导电性进行分析。结果表明,掺杂YB-CO体系的平均价电子数Zv与转变温度Tc、临界电流密度Jc之间有较好高斯分布规律。因此,提出用平均价电子数作为提高掺杂YBCO体系超导电性的一个新依据。这对今后制备出具有更高Tc、Jc的掺杂YBCO超导氧化物有很好的指导意义。