主成分回归法同时测定Cu2+、Pb2+、Hg2+和Cd2+

研究了用双硫腙光度法结合多元线性回归技术直接分析水相中有毒重金属离子的方法.结果表明,在β-环糊精和非离子表面活性剂Triton X-100的存在下,金属离子-双硫腙配位体系具有更高的灵敏度和稳定性.使用多元线性回归技术,可以在多种干扰金属离子共存的条件下,不经萃取和化学分离直接分析4种常见的有毒重金属离子.     

Heterometallic fullerides of Fe and Cu groups with the composition K2MC60 (M=Fe+2, Fe+3, Co+2, Ni+2, Cu+1, Cu+2, Ag+1)

Heterometallic fullerides with composition K₂MC₆₀, synthesized by exchange chemical reaction of K₅C₆₀ or K₄C₆₀ with chlorides of metals Fe and Cu groups have been investigated by X-ray diffraction, magnetic resonance, Raman and Mössbauer spectroscopy. Magnetization and susceptibility measurements have also been carried out. Metal chlorides from Fe and Cu groups enable to cover the whole range of electronic configuration of metal from d⁵ to d¹⁰. Heterometallic fullerides with M=Cu⁺², Fe⁺², Fe⁺³ and Ni⁺² appeared to be superconductors with T_c=13.9–16.5 K. Ferromagnetism and superconductivity coexist in investigated fulleride K₂Fe⁺³C₆₀.     

EPR study on Mn2+-Cu2+ and Ni2+-Cu2+ mixed pairs

An EPR study at X- and Q-band frequencies has been made on mixed metal pairs Mn²⁺-Cu²⁺ and Ni²⁺-Cu²⁺ obtained by doping the dimer complex C₅H₅NO CuCl₂ · H₂O. Available experimental data have been confirmed and extended, particularly as regards the characteristic directions of the various magnetic tensors. The qualitative behaviour of the spectra and the somewhat singular values of the magnetic parameters can be well-described on the basis of a theoretical model in which a very strong “cosine” interaction between the total electronic spins is assumed. From the model some interesting new aspects emerge, concerning the relations between pairs and single-ion EPR parameters.     

Relative equilibria of D2H + and H2D+

Relative equilibria of molecules are classical trajectories corresponding to steady rotations about stationary axes during which the shape of the molecule does not change. They can be used to explain and predict features of quantum spectra at high values of the total angular momentum J in much the same way that absolute equilibria are used at low J. This paper gives a classification of the symmetry types of relative equilibria of AB₂ molecules and computes the relative equilibria bifurcation diagrams and normal mode frequencies for D₂H⁺ and H₂D⁺. These are then fed into a harmonic quantization procedure to produce a number of predictions concerning the structures of energy level clusters and their rearrangements as J increases. In particular the formation of doublet pairs is predicted for H₂D⁺ from J ≈ 26.     

High pressure effect on the chemoselectivity of catalyzed [2+2] and [2+2+2] addition reactions involving acetylenic esters

Abstract

The chemoselectivity is changed by pressure in the catalyzed addition of propynoates to norbornadiene, but is not altered in the corresponding addition to norbornene.     

Properties of Ca-doped Bi2+xSr2−xCuO6+δ

Specific-heat measurement is performed for Ca-substituted samples for Sr in Bi_2.1Sr_1.9?yCa_yCuO_6+δ. Specific heat anomaly associated with the superconducting transition is observed for the samples for y = 0.8, 0.95 and 1.0. The anomalies are consistent with the behavior of the magnetic measurement and suggest the bulk effect of the 80 K-class superconductivity.     

Stoßdissoziation von H 2 + - und D 2 + -Ionen

The angular and energy distribution of protons produced by collision-induced dissociations of H ₂ ⁺ ions with energies of 10 and 20 keV were measured in a parabola spectrograph. From these measurements the velocity distribution of the protons in the center of mass system of the H ₂ ⁺ ion can be calculated. This gives information about the type, the abundance, and the anisotropy of the processes involved. The most frequent transitions leading to dissociations are the excitation of the 2pσ_u state, the ionisation of the H ₂ ⁺ ion, the transition into the vibrational continuum, and the electron capture into the 1³ σ _u ⁺ state of the hydrogen. It is shown that the cross section for an electronic transition depends on the velocity of the ion, the distance of the nuclei in the ion, the angle between the internuclear axis and the direction of the primary ion beam, and the excitation energy of the target. The fraction of protons produced by vibrational excitation increases with increasing atomic number of the target. Concerning electronic transitions D ₂ ⁺ ions equal H ₂ ⁺ ions of the same velocity.     

EPR study of Fe3+ and Mn2+ in CeO2 and ThO2

Attempts were made to grow CeO₂ and ThO₂ single crystals doped with transition metal ions. Only Fe³⁺ and Mn²⁺ could be detected by the EPR technique. The EPR spectrum of Fe³⁺ in CeO₂ exhibits the well-known fine structure in cubic fields. The parameters areg=2.0044(1) anda=15.6(1)·10^?4 cm^?1. The hyperfine constantA for⁵⁷Fe in hexahedral coordination was found to be 8.9(1)·10^?4 cm^?1. The EPR spectrum of Mn²⁺ in CeO₂ reveals two cubic Mn²⁺ centers. The parameters for center 1 areg=1.9999(1) andA=86.9(1)·10^?4 cm^?1 and for center 2g=1.9984(1) andA=87.0(1)·10^?4 cm^?1. Heating the Mn doped CeO₂ samples in hydrogen, the Mn²⁺ centers transform from cubic into trigonal centers with approximate values ofg=1.9988(2),A=84.5(6)·10^?4 cm^?1 andD=203(1)·10^?4 cm^?1. The two observed Mn²⁺ centers in ThO₂ exhibita priori axial symmetry with approximate values ofg=2.0006(2),A=88.9(4)·10^?4 cm^?1 andD=33(3)·10^?4 cm^?1.     

Efficiencies of third bodies in the reaction H + O2 + M = HO2 + M

Vibrational transition probabilities have been calculated by the Schwartz, Slawsky and Herzfeld method [3] for the deactivation of HO₂* in collision with H₂, O₂ and CO₂. The relative efficiencies of H₂, O₂ and CO₂ are compared with their third-body efficiencies found experimentally and it is concluded that the transfer of large vibrational quanta from HO₂* is unlikely to play an important part in determining the position of the second explosion limit of the H₂/O₂ reaction. This conclusion is at variance with the explanation put forward by Walsh [1] of the ‘anomalous’ third-body efficiencies of H₂O and CO₂ in this reaction.     

Co2+ and Mn2+ ion locations in doped CsCdCl3

Summary Substitutional Co²⁺ and Mn²⁺ ions at the two different Cd sites in the compound CsCdCl₃ have been studied by using electron paramagnetic resonance. The preferential occupation, Co²⁺ in the Cd_II site, Mn²⁺ in the Cd_I site, is discussed in terms of crystallochemical symmetry arguments. Paper presented at the ?V International Conference on Ternary and Multinary Compounds?, held in Cagliari, September 14–16, 1982.     

Nonradiative energy transfer from Mn2+ to Eu3+ in K2CaP2O7:Mn2+,Eu3+ phosphor

A series of color tunable phosphors K₂Ca_1?x?yP₂O₇:xMn²⁺, yEu³⁺ are synthesized by solid state reaction method. The energy transfer phenomenon from Mn²⁺ to Eu³⁺ has been observed in the Mn²⁺/Eu³⁺ codoped non-magnetic K₂CaP₂O₇ host, which was confirmed by PL spectra and decay curves. The Mn²⁺→Eu³⁺ energy transfer is controlled by quadrupole–quadrupole interaction between sensitizer and activator. The maximum efficiency of energy transfer is estimated to be 33% with x=0.125 and y=0.03 in K₂Ca_1?x?yP₂O₇:xMn²⁺, yEu³⁺ phosphor. The phosphors can emit light from green to yellow and eventually to orange under 400 nm excitation by changing the Mn²⁺/Eu³⁺ content ratio, indicating that K₂CaP₂O₇: Mn²⁺, Eu³⁺ would be potential candidates for use in lighting and displays applications.     

Mg2+、Zn2+掺杂CaWO4∶Eu3+荧光粉的发光性质

采用微波加热固相法合成了Mg2+、Zn2+掺杂CaWO4∶Eu3+荧光粉。利用XRD对样品的晶体结构进行表征,通过荧光分光光度仪对样品的激发光谱、发射光谱和能级寿命进行检测和分析。结果表明,Mg2+、Zn2+、Eu3+掺杂CaWO4不影响CaWO4基质的四方晶相。395nm激发下,与CaWO4∶2%Eu3+样品比较,分别掺杂0.5%的Mg2+或Zn2+的样品发光强度提高了1.3倍和2.1倍;与3%Mg2+或3%Zn2+掺杂CaWO4∶2%Eu3粉体发光比较,当Eu3+浓度增加为3%时,粉体的发光强度分别提高了7.3倍和14.8倍;与CaWO4∶3%Eu3+样品比较,3%的Mg2+或Zn2+掺杂后的样品光强分别提高了1.2倍和1.3倍。262nm比395nm激发同一样品的Eu3+的5D0能级寿命有所增加。与单掺2%Eu3+样品比较,随着Mg2+或Zn2+掺杂浓度增加,样品荧光寿命先增加后减小。同样激发波长下,与Mg2+或Zn2+掺杂CaWO4∶2%Eu3+样品荧光寿命相比,Eu3+浓度增加为3%时,样品的荧光寿命明显变短。     

Eu2+在磷酸镧中的发光及Ce3+→Eu2+的能量传递

采用高温固相反应合成了LaPO₄:Eu²⁺和LaPO₄:Ce³⁺,Eu²⁺样品,报道了Eu²⁺在LaPO₄中的发光性质和Ce³⁺→Eu²⁺的能量传递现象。文中探讨了Ce³⁺→Eu²⁺的能量传递机理,根据Dexter电多极相互作用的理论证明其为偶极子偶极子相互作用的共振能量传递。     

Geometry of C2N2 + and HCN+ from low-energy photoelectron spectroscopy

Quantitative Franck-Condon calculations are applied to the first two band systems of the low energy photoelectron spectrum of dicyanogen (C₂N₂) and to the first band system of hydrogen cyanide. Estimates are made of the bond length changes from the ground electronic state of the molecule to various states of C₂N₂ ⁺ and to the ground state of HCN⁺. These changes are consistent with expectations based on simple molecular orbital theory.

It is shown that there is sufficient intensity in the perturbed first system of HCN, and also that of DCN, to account for an overlapping second system due to the removal of an electron from the 5σ orbital.     

Local coordination of Co2+ and Ni2+ cations in polyacrylate matrices

Parameters of the local coordination of Co²⁺ and Ni²⁺ cations in polymer matrices are determined by XAFS spectroscopy at the K edges of the corresponding elements. Ion-exchange complexes of Ni²⁺ and polymethacrylate, low-molecular acrylamide complexes [M(CH₂=CHC(O)NH₂)₆](NO₃)₂ (M = Co or Ni), and products of their thermal polymerization are investigated. The final results are in agreement with the octahedral coordination of M atoms (average distances, 2.10–2.11 (Co-O) and 2.05–2.06 Å (Ni-O).     

N2O+离子A2∑+电子态的光解动力学研究

用一束波长为360.55nm的激光,通过N2O分子的(3+1)共振多光子电离(REMPI)过程制备纯净且布居完全处于X2Ⅱ(000)态的母体离子N2O+,然后用另一束波长在275-328nm范围内的可调谐激光将制备的N2O+离子激发至预解离电子态A2∑+.实验发现,由于解离碎片NO+所具有的一定的反冲速度,其TOF质谱峰明显比N2O+母体宽.通过分析NO+碎片TOF质谱峰形状,得到了解离产物的总平均平动能;通过考察随光解能量的变化,发现光解能量在32000cm-1附近约250cm-1的变化范围内,值由约8000cm-1突然减小至约1600cm-1.通过分析,在光解能量小于32000cm-1的区域,解离通道为NO+(X1∑+)+N(4S);而在光解能量大于32000cm-1的区域,另一个具有较高解离限的解离通道,NO+(X1∑+)+N(2D),开启并完全取代N(4S)通道成为解离的惟一通道.根据实验结果,对在所研究的光解能量范围内的N2O+离子A2∑+电子态预解离机理进行了探讨.     

Luminescence of Ln3+ and WO 2 2+ ions in wolframylphosphate glasses

We investigate the luminescent properties of potassium wolframylphosphate glasses doped with Eu³⁺, Tb³⁺, and Dy³⁺ ions whose luminescence is excited by donor-acceptor interaction between the active WO ₂ ²⁺ and Ln³⁺ ions, as well as the migration of energy in the subsystems of each type of the active ions. Comparison of the obtained data with the results of investigation of the spectroscopic properties of Ln³⁺ in uranylphosphate materials shows that a sufficiently high degree of the ionicity of bonds of Ln³⁺ with the atoms of its first coordination sphere is preserved in wolframylphosphate matrices. We show that three stages of the decomposition of electron excitations are typical of the WO ₂ ²⁺ ions in wolframylphosphate glasses doped with Ln³⁺ and two stages in nonactivated glasses. The electron excitation energy transfer in the WO ₂ ²⁺ −Ln³⁺ system occurs due to induction-resonance interaction. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 5, pp. 620–625, September–October, 1997.     

Conservation Laws and Bianchi Identities in R+R2+Q2 Theories

We investigate the conscrvalion Jaws in the class of R+R²+Q² theory with torsion. We prove that the conservation Jaws may be dcrived Born the Bianchi identities of the curvature and torsion tensors. In particular the conservation law for matter is showed to be a result of the Dianchi identities and gravitational ficld equations just as it does for T^uv=0 in general relativity.