固体ASm2I5的d-f跃迁荧光和反射光谱(A=K,Rb,Cs,T1)

本文系统地研究了化合物ASm2I5(A=K,Rb,Cs,T1)固体粉末的荧光光谱和反射光谱.讨论了Sm2+在立方晶体场中的分裂能随着碱金属离子半径的增大而减小和f-d激发能随着A-I(A=Rb,T1)键的共价性增加而明显降低的现象.并从晶场效应和化学键性质两个方面解释了ASm2I5(A=K,Rb,Cs)和ASm2I5(A=Rb,T1)中的Sm2+荧光光谱分别发生蓝移和红移的现象.     

M+AsF6-(M=Li,Na,K,Rb和Cs)离子对的结构和振动光谱

利用abinitio计算方法研究了AsF6-阴离子和M AsF6-(M =Li ,Na ,K ,Rb 和Cs )直接接触离子对的结构和光谱行为。结果表明,具有C3V结构三齿相互作用的M AsF6-最稳定,二齿配位的结构只有在特定条件下才可能稳定存在。当形成离子对后,阳离子与AsF6-的相互作用将改变AsF6-的结构,这其中Li 的影响最大。另外,AsF6-光谱的变化可用来指认溶液中离子的缔合和离子对的种类。     

关于在AMgF_3(A=K,Rb,Cs)中Eu~(3 )的~5D_0能级的位置

Eu~(3 )的发光是人们所熟悉的。主要地从~5D_0能级起源,跃迁到~7F_J簇。在Eu~(3 )的发射光谱中,一般地是~5D_0-~7F_2或~5D_0-~7F_1谱线占优势。如果Eu~(3 )离子占有一个位置,该位置的对称允许是线性晶体场项,则~5D_0-~7F_0跃迁仅仅具有可以测量的强度。本工作涉及在AMgF_3(A=K,Rb,Cs)晶格中~5D_0能级的位置。这种位置是由在这些晶格中具有适当强度的~5D_0-~7F_0发光跃迁得来的。     

A comparison of the197Au Mössbauer spectra of MAu (M=K,Rb, Cs) with (2, 2, 2-crypt M) Au

Gold-197 Mössbauer spectroscopy has been used to investigate the MAu system (M=K, Kb, Cs). Of the 11 alloys RbAu and CsAu give Mössbauer spectra consistent with cubic gold environments, while (2,2,2-crypt M) Au, (M=K, Pb, Cs) all have cubic gold environments. Comparison of the isomer shifts for the crypted and uncrypted salts leads to the conclusion that in RbAu and CsAu considerable electron density is removed from the gold 5d orbitals.     

Optical spectroscopy studies on FeTelxSex and AxFe2uSe2 （A = K, Rb, Cs）： A brief overview

In this short overview, we summarize the optical spectroscopy FeTezxSex and AxFe2-ySe2. We elaborate that optical spectroscopy band structure evolution across the AFM phase transition temperature, studies on iron selenide superconducting systems measurements yield fruitful information about the the electronic correlation effect, the superconduct- ing pairing energy gap, the condensed carrier density or penetration depth, the inhomogeneity and the nanoscale phase separation between superconductivity and antiferromagnetism in those systems.     

Electrical properties of A′Ca2Nb3O10 (A′=K, Rb, Cs) layered perovskite ceramics

The electrical conductivity properties of Dion-Jacobson type layered perovskites A′Ca₂Nb₃O₁₀ (A′=K, Rb, Cs) was investigated under different gas atmospheres. An increase in the electrical conductivity by about 2–5 orders in magnitude in both ammonia and hydrogen atmospheres is observed compared to air. Among the members of the series, the compound with the smallest size of the alkali ion, i.e. KCa₂Nb₃O₁₀, exhibits the highest conductivity. In air and hydrogen, a single activation energy value in the range 0.25 – 0.80 eV is observed, while in ammonia a sharp increase in the electrical conductivity is found at about 500 °C. The activation energy at low-temperatures (300–500 °C) is attributed to ionic motion and at higher temperatures (500–700 °C) to both defect formation and ionic motion. The unusual electrical conductivity behavior in ammonia is explained on the basis of the model developed for alkali halides. EMF measurements reveal that the layered perovskites are ionic (proton) conductors. The electrical conductivity changes as a function of the ammonia gas concentration; accordingly, layered perovskites appear to be useful solid electrolytes in galvanic cells for practical applications, e.g. for gas sensors. Paper presented at the 7th Euroconference on Ionics, Calcatoggio, Corsica, France, Oct. 1–7, 2000.     

ACl-CeCl_3(A=Li,Na,K,Cs)体系表面张力的计算

对二元系NaCl-CeCl_3进行了热力学优化,得到一套能够合理描述该体系的热力学参数,计算出的相图及其他热力学数据与实验值吻合良好。由CALPHAD方法得到了热力学数据库,并结合Butler方程对含稀土金属氯化盐的熔盐体系表面张力的计算模型进行了修正,计算了ACl-CeCl_3(A=Li,Na,K,Cs)体系的表面张力。结果显示,描述体系表面相和体相吉布斯能关系的模型参数β与体系类别密切相关,对于本文所计算的熔盐体系,β值随碱金属离子半径的增大而增大。本文还探讨了熔盐体系中表面相与体相组分之间的关系。     

Rb(5PJ)+Rb(5PJ)→Rb(5S)+Rb(nl=5D,7S)碰撞能量合并

研究了Rb(5PJ) Rb(5PJ)→Rb(nlJ') Rb(5S)碰撞能量合并过程,利用单模半导体激光器分别共振激发Rb原子的5P1/2或5P3/2态,利用另一与泵浦激光束反向平行的单模激光束作为吸收线探测激发态原子密度及其空间分布,吸收线分别调至5P1/2→5D3/2和5P3/2→7S1/2跃迁.由激发态原子密度和谱线荧光比得到碰撞能量合并过程的截面,对5P3/2激发,碰撞转移得到5D5/2,5D3/2和7S1/2的截面分别是(1.32士0.59)×10-14,(1.18士0.53)×10-14和(3.21士1.44)×10-15cm2;对5P1/2激发,碰撞转移到5D5/2和5D3/2的截面分别是(6.57士2.96)×10-15和(5.90士2.66)×10-15cm2.与其他的实验结果进行了比较.     

β型烧绿石结构氧化物超导体AOs2O6(A=K,Rb,Cs)电子能带结构的第一性原理计算

用全势线性缀加平面波方法计算β型烧绿石结构氧化物超导体AOs2O6(A=K,Rb,Cs)的电子能带结构及态密度.计算发现电子自旋轨道耦合和在位库仑势U的作用增大了费米面处态密度值.通过计算还得到这三种化合物电子关联常数λc分别为1.55,1.12和0.73.由实验测量与能带计算得到的电子比热容系数的比值得到电子质量提高参数.通过分析这三种化合物电子质量提高参数,推算出它们的电声子耦合常数λep分别为1.56,0.78和1.08.由此提出KOs2O6为强电子关联和强电声子耦合系统,而RbOs2O6和CsOs2O6的电子关联性与电声子耦合为中等.     

Energy-pooling collisions in Rb-Cs vapor mixture Rb(5P_J)+Cs(6P_(3/2))→Rb(5S_(1/2))+Cs(nl_(J''''))

Rate coefficients for energy-pooling (EP) collisions Rb(5PJ) Cs(6P3/2)→Rb(5S1/2) Cs(nlJ') have been measured. Atoms were excited to Rb(5PJ) and Cs(6P3/2) states using two single-mode diode lasers. To isolate the heteronuclear contribution in the fluorescence spectrum, a double-modulation technique has been adopted. The excited-atom density and spatial distribution are mapped by monitoring the absorption of a counterpropagating single-mode diode laser beam, tuned to Rb(5PJ→7S1/2) and Cs(6P3/2→8S1/2) transitions respectively, which could be translated parallelly to the pump beams. The excited atom densities are combined with the measured fluorescence ratios to determine cross sections for the EP processes. It was found that Rb(5P1/2) Cs(6P3/2) collisions are more efficient than Rb(5P3/2) Cs(6P3/2) collisions for populating Cs(4F5/2), while the opposite is true for populating Cs(4F7/2).     

A2Ca[B4O5(OH)4]2·8H2O(A＝Rb, Cs)合成、 FTIR光谱及激光拉曼光谱研究

采用Rb2 CO3 ,Cs2 CO3 ,H3 BO3 和CaCl2 合成了新的硼氧酸盐复盐Rb2 Ca[B4O5(OH) 4 ]2 ·8H2 O和Cs2 Ca[B4O5(OH) 4 ]2 ·8H2 O ,通过化学分析和热分析等确定了化学物的组成。给出了两种化合物的FTIR光谱和Ra man光谱 ,分析了各种谱线的归属。     

Tb1-xGdxA3(A=邻氨基苯甲酸,x=0-1)固体配合物的光谱分析和荧光增强

合成了一系列组成为Tb1-xGdxA3(A=邻氨基苯甲酸，x=0-1.0)的固体配合物。利用红外光谱和荧光光谱研究了配合物的结构和荧光性质。红外光谱的结果表明，掺表配合物的结构与未掺杂的邻氨基苯甲酸铽相似。荧光光谱的结果显示，Gd^3 对Tb^3 的发光有明显的增敏作用，并对荧光增敏的机理进行了探讨。     

碰撞能量转移Cs(6P)+Cs(5D)→Cs(6S)+Cs(nL=9S,5F)的截面测量

二步激发Cs原子至8S态,测量了碰撞转移过程Cs(6P)+Cs(5D)→Cs(6S)+Cs(nL=9S,5F)的截面,测量由7D,9S和5F态发射的荧光强度,从荧光强度比和σ(7D)值得到了σ(9S)和σ(5F),而σ(7D)已经进行过绝对测量,截面值σ(9S)和σ(5F)分别为8.7×10-15和1.3×10-14?cm2.讨论了能量转移过程9S+6S5F+6S对σ(9S)和σ(5F)的影响.     

Electron excitation energy transfer in Me7Eu2UO2(PO4)5 (Me — Na, Rb, Cs) crystals

The article considers the luminescence-kinetics properties of crystals of ternary uranyl orthephosphates Me₇Eu₂UO₂(PO₄)₅ (Me — Na, Rb, Cs) obtained by the methods of solid-phase synthesis. The main parameters of conversion of the electron excitation energy in the donor-acceptor UO ₂ ²⁺ —Ln³⁺ system are determined. The competition between the processes of nonradiative dissipation and energy transfer from UO ₂ ²⁺ to Eu³⁺ has been revealed. It is shown that the rate of the processes of nonradiative transitions in the uranyl complex is determined by the degree of distortion of its local field, while the luminescence lifetime of the acceptors depends on the energy of electrostatic interaction between Eu³⁺ and oxygen atoms of its first coordination sphere. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 3, pp. 333–335, May–June, 2000.     

Tb1-xLnxA3(A=对氨基苯甲酸,x=0-0.9)固体配合物的光谱分析和荧光增强

合成了一系列组成为 Tb1-x Lnx A3 (L n=Gd、Y、La,A=对氨基苯甲酸 ,x=0— 0 .9)的固体配合物。利用红外光谱和荧光光谱研究了配合物的结构和荧光性质 ,结果表明 ,掺杂配合物的结构与未掺杂的对氨基苯甲酸铽相似。荧光光谱的结果显示 ,Gd3 对 Tb3 的发光有明显的增敏作用 ,探讨了荧光增敏机理。     

Elastic and thermodynamic properties of alkali hydrides XH (X = K,Rb and Cs)

The calculation of the structural, mechanical and thermodynamic properties of the alkali hydrides XH (X?=?K, Rb and Cs) in rock-salt (RS), cesium chloride (CsCl), zinc-blende (ZB) and wurtzite (WZ) phases are done by using the full-potential linearized augmented plane wave (FP-LAPW) method within the frame work of the density functional theory (DFT) as implemented in the WIEN2K code. The Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA) was used for the exchange-correlation potential.The elastic constants and their related properties, as well as the thermodynamic properties, were obtained by using the IRelast package. The calculated elastic constants for the alkali hydrides, with the four structures RS, CsCl, ZB and WZ, at ambient pressure are mechanically stable. The elastic constants and their related properties in the RS structure are changeable with increasing pressure. Elastic constants, bulk modulus, shear modulus (stiffness) and Debye temperatures of these compounds are decreased as going from K to Cs in the periodic table. These compounds in the RS structure are mechanically stronger at ambient conditions.     

吡啶-水团簇(C_5H_5N)_n(H_2O)_m(n=1～2,m=1～4)结构和红外光谱的理论研究

利用密度泛函理论,在B3LYP/6-311++G(d,p)基组水平上对吡啶-水团簇(C5H5N)n(H2O)m(n=1~2,m=1~4)的可能构型进行全优化,得到了团簇的稳定结构;计算结果显示,在吡啶和水的二聚体中,稳定构型只有一种,没有发现通过π氢键(O—H…π)作用形成的团簇结构。为了研究各团簇结构的稳定性,在相同的基组水平上计算得到了各团簇构型的总能量和结合能,结果显示,对于团簇(C5H5N)n(H2O)4(n=1~2),团簇中的水分子形成四元环的结构要比形成三元环的结构稳定。对团簇的最高占据轨道与最低空轨道之间的能隙分析发现,团簇C5H5N(H2O)4的最低能量结构具有较高的稳定性,可能具有幻数结构;最后,分析讨论了吡啶-水团簇的红外振动光谱,对较强的谱峰进行了指认。     

内嵌复合物M@C60（M=Li,Na,K,Rb,Cs）的分子力学研究

利用分子力学方法计算了碱金属内嵌复合物Ｍ＠Ｃ６０中Ｍ与Ｃ６０之间的相互作用，考察了Ｍ在Ｃ６０笼内的平衡位置。研究表明Ｌｉ和Ｎａ的平衡位置偏离Ｃ６０分子的中心，Ｋ、Ｒｂ和ＣＳ的平衡位置在Ｃ６０分子的中心。平衡位置的确定取决于色散作用和排斥作用的大小。最后，讨论了碱金属原子进入笼内的可能机制。