Vibrational-electronic coupling in IrF6, OsCl6 2− and IrCl6 2−

The results obtained in a previous paper [1] for an unsymmetric regular model are applied to solid hydrogen at low temperatures when the lattice structure and the quadrupole-quadrupole interaction make the interaction energies non-isotropic. It is shown that, as for the lattice structures with isotropic interactions, no second-order transition is likely to occur through a cooperative rotational effect. The possible occurrence of spatial ordering on sub-lattices is discussed. It is found that such ordering is unlikely to occur at low temperatures on the face-centred cubic lattice, but that on the hexagonal close-packed lattice (which is the probable crystal structure) there is a second-order transition to an ordered state. Using a zeroth-order approximation the temperature at which this transition occurs in pure ortho-hydrogen is found to be 5·8°k.     

Ba_2CaWO_6-Sr_2CaWO_6赝二元系的研究

用差热分析、X射线物相分析和点阵常数的精确测定,研究了Ba_2CaWO_6-Sr_2CaWO_6赝二元系的相平衡和相变。发现在高温(860℃以上)时,形成连续固溶体。在室温时,在富Ba_2CaWO_6一侧,形成以Ba_2CaWO_6为基的固溶体;在富Sr_2CaWO_6一侧,形成以Sr_2CaWO_6为基的固溶体,相变点在成分为Ba_2CaWO:Sr_2CaWO_6=25:75(克分子比)处。 同时研究了作为高压钠灯灯丝涂层材料的Ba_xSr_(2-x)CaWO_6的几个重要性质:电子发射和多次启动时的灯压升高等。发现成分为BaSrCaWO_6时,性质最好。     

Spin-spin interaction of Ni2+ ions in ZnSiF6·6H2O

The angular dependences of the electron spin resonance spectrum of 1% Ni²⁺ ions in a ZnSiF₆·6H₂O matrix are investigated experimentally at 36 GHz and 4.2 K. Besides the main spectrum of the isolated ion, we observed a spectrum due to interacting pairs of Ni²⁺ ions, located in the first (nn) and second (2n) coordination spheres and coupled by, besides the magnetic dipole-dipole interaction, isotropic exchange: J _nn = (−197±1)×10⁻⁴, J _2nα = (−5±1)×10⁻⁴, and J _2nβ = (3±2)×10⁻⁴ cm⁻¹. Lines due to other isolated Ni²⁺ ions, which have a different initial splitting D, are also present in the spectrum with intensity comparable to the pair spectrum. Low-symmetry distortions of the crystal field are observed, caused by a pair of impurity ions located close to one another. It is shown that the previously proposed interpretation is incorrect. Fiz. Tverd. Tela (St. Petersburg) 41, 1602–1608 (September 1999)     

钡原子6s~2、5d~2、6p~2组合的电子相关效应及其组合相互作用

用模型势方法和斯莱特-高登(Slater-Condon)理论计算了钡原子偶宇称6s~2,5d~2,6p~2电子组合、角动量J=0,1,2的双激发能级的激发能和组合相互作用(configuration interaction)。结果表明,6s~2,5d~2和6p~2组合在~1S_0态中强烈地混合,使常规能级标识符号失去意义。另外,我们的结果也从理论上证明了曾引起争议的6p~(21)S_0能级是位于第一电离势之上的自由离能级。     

4 Ag ↔2 Eg Transition of Mn4+ in Cs2TiF6: MnF6 2-

We report and interpret the ⁴ A_2g ?² E_g absorption, emission, linear dichroism, MCD and MCE of the MnF₆ ^2- octahedra at sites of D_3d symmetry in single crystals of Cs₂TiF₆. The spectra show many sharp features but a simplified calculation using cubic basis functions successfully accounts for all of the major features and much of the detailed structure. The electronic levels are not split by the trigonal field in first order but trigonal distortion splits the three-fold degenerate v ₆(t_2u ) vibration of the octahedron into a two-fold degenerate v ₆(e_u ) and a non-degenerate v ₆(a_1u ) vibration and these two vibrational modes give rise to the features 213 cm^-1 and 246 cm^-1 from the zero-phonon line respectively. Similarly the v ₄(t_1u ) vibration is split into a v ₄(a_2u ) and v ₄(e_u ) vibration and give the features at 313 cm^-1 and 340 cm^-1 respectively.

Several transitions involving two or more quanta of vibration are clearly seen in the emission and MCE spectrum. At an energy shift of greater than 700 cm^-1 from the zero-phonon transition these features are found to consist of progressions in the v ₁(a_1g ) breathing mode and the v ₂(e_g ) two-fold degenerate Jahn-Teller active mode. This structure can again be explained, with one exception, in terms of a calculation which assumes cubic basis functions. The exception is the reversal in sign of the MCE at a frequency v ₆(e_u ) + v ₂(e_g ) compared with that at v ₆(e_u ) which is not fully understood.     

Chemical effects of nuclear transformations in mixed crystals. 13. chemical effects of the 79Br(n, γ)80mBr nuclear reaction in K2OsBr6-K2OsCl6, K2ReBr6-K2ReCl6, and K2OsBr6-K2SnCl6 mixed crystals [1]

The solid-state reactions occurring during the moderation of (n, γ) produced hot ^80mBr were studied in K₂OsBr₆-K₂OsCl₆, K₂ReBr₆-K₂ReCl₆, and K₂OsBr₆-K₂SnCl₆ mixed crystals. The formation of the main reaction products M^80mBrBr5/2-, M^80mBrCl5/2- (M = Re, Os), Os^80mBrBr₄Cl^2-, and ^80mBr^- is attributed to the following reaction channels: (1) primary retention or bond-preservation because of insufficient recoil energy, (2) billiard-ball reaction (substitution or replacement of ligands by recoil ^80mBr), (3) substitution as in (2) but formation of an additional ligand vacancy which is filled by an adjacent halide ion, and (4) capture of ^80mBr at interstitial vacancies. From the experimental results the contributions of these reaction channels were evaluated quantitatively.     

Magic Wavelength for Caesium Transition Line 6S1/2 - 6P3/2

We investigate the magic wavelengths of the trapping laser for 6S1/2 - 6P3/2 Of the Cs atom in a region where the optical shift between two different states can be elirninated. For fine levels and linear polarized laser they are 930.4 nrn and 937.2nm. The magic wavelengths range from 927. 7nrn to 945.0nm for circle-polarized perturbing laser. Effects of nuclear spin, the hyper-fine Zeernan levels, and the polarization of the light, which generate different magic wavelengths, are further discussed.     

Cu_6Si_6O_18·6H_2O中Cu~（2＋）的吸收光谱和g因子研究

在晶体场理论基础上，该文得到３ｄ９离子在伸长四角畸变晶场中的电子能级和三阶微扰的ｇ因子公式。作为公式的应用，文中研究了晶体Ｃｕ６Ｓｉ６Ｏ１８６Ｈ２Ｏ内Ｃｕ２＋离子的电子吸收光谱和ＥＰＲｇ因子，理论计算与实验结果进行了比较     

Phase transition studies in CoSiF6·6H2O and Co1−xZnxSiF6·6H2O by Mn(II) EPR

Phase transition studies on single crystals of CoSiF₆·6H₂O and Co_1−xZn_xSiF₆·6H₂O (x = 0.082, 0.182, 0.248) using Mn(II) EPR at X-band were carried out in the temperature range 10–300 K. Phase transitions with considerable thermal hysteresis have been detected in CoSiF₆·6H₂O and Co_1−xZn_xSiF₆·OH₂O (x = 0.082, 0.182). In CoSiF₆·6H₂O, the transition temperatures during cooling (T^c_c) and during heating (T^h_c) were found to be considerably less than those obtained previously from magnetic anisotropy experiments, i.e. 230 and 246 K as against 246 and 259 K. These characteristic temperatures for the dilute crystals having x = 0.082 and 0.182 were 205, 218 K and 175, 185 K, respectively. It is thus evident that magnetic dilution with zinc causes a progressive reduction in the transition temperatures as well as in the thermal hysteresis. The phase transition manifests itself in a large discontinuous increase in the Mn(II) zero-field splitting parameter (D), i.e. from −187 ± 1 G to −290 ± 1 G, in these crystals. The hyperfine coefficient (A) also increases discontinuously from 99 ± 1 G to 102 ± 1 G at T_c. In the dilute crystal with x = 0.248 a very slow continuous decrease in D and practically no change in A have been detected with a lowering of the temperature. A small temperature independent positive g-shift (g = 2.020 ± 0.005) has been observed in all the crystals studied. The spin-lattice relaxation time (T₁) of the Co(II) ion in CoSiF₆·6H₂O at different temperatures, both above and below T_c, has been estimated from the observed Mn(II) hyperfine linewidth. A discontinuous change in T₁ at T_c has been observed. Analysis of the temperature dependence of the linewidth has further revealed that a two-level Orbach process describes well the thermal behaviour of the spin-lattice relaxation of the Co(II) ions in these crystals. The location of the first excited level in CoSiF₆·6H₂O determined from such studies at temperatures both above and below T_c has been examined in the light of the ligand field energy scheme of the Co(II) ion in an octahedral field. It is concluded that the phase transition in this crystal is probably accompanied by a change in sign of the axial field parameter (Δ).     

单斜辉石固溶体CaMgSi2O6—N4AlSi2O6的合成机理研究

研究了压力和温度对单斜辉石的结晶和晶粒纤维编织的影响。在较低的晶化温度下压力对单斜辉石结晶的影响很明显，这种影响随温度升高而减弱。然而，压力对单斜辉石晶粒纤维编织的影响正相反，在相同的高温下，较高压力下晶化的单斜辉石晶粒纤维比较低压力下得到的晶粒纤维粗壮，而且编织紧密。     

铅原子6p7s—6p^2多重态谱线

原子内部各种相互作用决定原子能级,能级结构决定其原子光谱。本文以铅原子6p7s—6p~2跃迁所辐射的多重态谱线为例,计算各能级,分析电、磁性作用强弱。原理铅原子Z=82,基态电子组态[Xe]4f~(14)5d~(10)6s~26p~2,简记6p~2,基本属于LS耦合类型,该电子组态耦合各支能级(谱项),近似地遵循。     

Molecular Constants of MnF6 −2 Anion

Abstract

The normal coordinate analysis of XY₆ type of anions and molecules employing different force fields is well established.^1,2 Recently, the vibrational spectra and complete frequency assignment of MnF₆ ^?2 has been reported by Flint.³ Using the available vibrational data the force constants have been evaluated employing three potential models viz. general valence force field (GVFF), Urey-Bradley force field (UBFF) and orbital valence force field (OVFF). The mean amplitudes of vibration and Bastiansen-Morino shrinkages have also been computed at two temperatures.     

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基于中国氦冷固态实验包层模块(CH-HCSB-TBM)的新设计方案,采用蒙特卡罗粒子输运程序MCNP和欧洲活化计算程序FISPACT,对CH-HCSB-TBM进行了三维活化计算分析.计算结果表明,停堆初期TBM总的放射性活度、衰变余热分别为1.78× 1016Bq和3.01kW,主要受结构材料CLF-1影响.同时给出了影响TBM材料活化特性的主要核素及其生成途径,为TBM设计的材料选取和优化提供依据.根据计算的停堆剂量率可知,TBM中的活化材料都能采取远程操作实现再循环利用,可有效防止放射性环境危害问题.     

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基于中国ITER氦冷固态增殖剂实验包层(CH HCSB TBM)最新2×6模块化结构设计,用三维中子输运计算程序MCNP/4C和相应数据库,对ITER实验包层模块设计的中子学问题进行计算分析,计算出在实际运行工况下,氚增殖率为0.0123g.d-1,整个TBM内的核热沉积为0.587MW。在各材料区内,最高功率密度为6.26MW.m-3,同时给出了不同材料区的功率密度。     

Thermal-energy Pooling Collisions in Cesium Vapor 6P_(3/2) 6P_(3/2) →7P_J 6S_(1/2)

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A modification potential method of calculating total cross sections of electrons scattering from complex molecules C2H6, C2F6, C6H6 and C6F6 at 100 eV-5000 eV

A complex optical model potential modified by incorporating the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between two atoms in a molecule, is first employed to calculate the total cross sections for electrons scattering from such complex molecules as C总交叉断面 电子散射 添加规则 原子分子碰撞 电子云total cross section, electrons scattering, additivity rule, atomic and molecular collisionProject supported by the National Natural Science Foundation of China (Grant No 10574039).2005-11-102005-11-102005-11-30A complex optical model potential modified by incorporating the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between two atoms in a molecule, is first employed to calculate the total cross sections for electrons scattering from such complex molecules as C2H6, C2F6, C6H6 and C6F6 using the aclditivity rule model at Hartree-Fock level over the energy range from 100 eV to 5000 eV. The total cross sections are quantitatively compared with those obtained by experiments wherever available, and they are in good agreement with each other over a wide energy range. It is shown that the modified potential together with the additivity rule model is completely suitable for the calculation of total cross sections of electrons scattering from such complex molecules as C2H6, C2F6, C6H6 and C6F6 above 200 eV-300 eV.     

Tl2Ba2CuO6布里渊区中心声子模的计算

本采用简单力常数模型计算了Ｔｌ２Ｂａ２ＣｕＯ６布里渊区中心声子模的频率，给出了与各声子模相应的原子振动位移图，计算结果和实验值符合得很好，对于高Ｔｃ超导体，原子间相互作用的力常数随结构变化很小。     

Na2Ca6La2(PO4)6F2:Eu3+的荧光和结构的局部对称性

稀土Eu3+离子的荧光谱线的数目、位置和强度与其所处的周围环境对称性有明确的联系。为了测定La3+离子在Na2Ca6La2(PO4)6F2相中所处格位的对称性,合成样品时,适量掺杂Eu3+离子,得到Na2Ca6La2-x(PO4)6F2:Eux红色荧光体。研究此种发光体的荧光光谱性质,能够证实La3+在Na2Ca6La2(PO4)6F2中处于两种不同的对称格位(D3h和C6)。