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61.
The High Temperature Superconductors are characterized by a very anisotropical structure and by typical arrangements of Cu- and O-atoms within CuO2-planes. In studying the electronic structure of these compounds there is a strong demand for high resolution valence band spectroscopy. Using an electron probe microanalyzer we study the X-ray emission of O-Kga and Cu-L emerging from polycrystalline YBa2Cu3O7 and Tl2Ba2Ca2Cu3O10. The O-K emission band is analyzed using a chlinochlore crystal in (001) orientation (2d = 28.4 Å). For the Cu-L emission band we use a beryl crystal in (10¯10) orientation (2d = 15.9 Å). Furthermore, orientation dependent X-ray emission spectroscopy of single-crystalline YBa2Cu3O7 and Tl2Ba2Ca1Cu2O8 specimens was performed. We present the partial O-K spectra which represent the O-2p ( = x, y, z) electronic densities of states of the valence band and compare them with calculated data. 相似文献
62.
本文利用电感耦合等离子体原子发射光谱多色仪的扫描功能,用卡尔曼滤波法对各种光谱干扰进行校正。结果表明,该法能处理各种类型光谱干扰,不需要样品基体匹配,其测定回收率明显优于在峰法和离峰法,具有简便、准确等优点。 相似文献
63.
Dulal C. Ghosh 《Journal of Chemical Sciences》1984,93(1):33-46
A cndo/2D study of the charge distribution obtained through Mulliken population analysis in the ground state of the title
compounds shows that the features of charge distribution found by severalab initio calculations are fairly well reproduced by this method. The one-particle density, the interference density at the mid-point
of the bond axis and the kinetic part of the interference energy calculated through the deorthogonalized density matrices
over a wide range of intermolecular separation between the donor and the acceptor show that the one-particle density and the
interference density steadily grow with decreasing internuclear separation, while the kinetic interference energy starts with
negative value at large distance, then decreases and passes through a minima near but above the equilibrium distance and then
increases rapidly below it conforming to the characteristic general behaviour of the kinetic component of Morse curve. The
orbital pairwise interference density and the corresponding kinetic energy components reveal that the orbitals involved in
the covalent binding are σ2p AO of B and 2S and σ2p AO of N and C atoms in H3B-NH3 and H3B-CO respectively. 相似文献
64.
海底沉积物的ICP-AES分析 总被引:1,自引:0,他引:1
海底沉积物用硝酸-高氯酸-氢氟酸消解,然后用ICP-AES法同时测定常量和微量元素。研究了样品中基体元素对微量元素测定的光谱干扰,并采用干扰曲线斜率法进行干扰校正,分析批量海底沉积物样品获得满意结果。 相似文献
65.
66.
Interactions between divalent alkali earth metal (DAEM) ions M (M?Be, Mg, Ca, Sr, Ba) and the second stable glycine conformer in the gas phase, which can transfer into the ground‐state glycine‐M2+ (except the glycine–Be2+) among each corresponding isomers when these divalent metal ions are bound, are studied at the hybrid three‐parameter B3LYP level with three different basis sets. Proton transfers from the hydroxyl to the amino nitrogen of the glycine without energy barriers have been first observed in the gas phase in these glycine–M2+ systems. The interaction between the glycine and these DAEM ions except beryllium and magnesium ion only create an amino hydrogen pointing to the original hydroxyl due to their weaker interaction relative to those divalent transition metal (DTM) ion‐bound glycine derivatives, being obviously different from that between the glycine and DTM ions, in which two amino hydrogens point to the original hydroxyl oxygen when these metal‐chelated glycine derivatives are produced. The interaction energy between the glycine and divalent magnesium would be the boundary of one or two amino hydrogens pointing to the hydrogyl oxygen, i.e., the ?170.3 kcal/mol of binding energy is a critical point. Similar intramolecular proton transfer has also been predicted for those DTM ion‐chelated glycine systems; however, that in the gas state has not been observed in the monovalent metal ion‐coordinated glycine systems. The binding energy between some monovalent TM ion and the glycine is similar to that of the glycine–Ba2+, which has the lowest binding strength among these DAEM–ion chelated glycine complexes. The difference among them only lies in the larger electrostatic and polarized effects in the latter, which favor the stability of the zwitterionic glycine form in the gas phase. According to these observations, we predict that the zwitterionic glycine would exist in the field of two positive charges in the gas phase. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 205–214, 2003 相似文献
67.
68.
A fundamental difficulty in theoretical physics is the dual and apparently incompatible interpretations of radiation as showing both continuous and extensive wave properties but also those of discrete atomic or smaller individual particles. Some of these contradictions are outlined. The explanation offered is of a quantized nature of time; units to=h/moc2 for a particle at rest, and of similar interval unit so when in relative motion, with conventional relativistic corrections.
For many purposes this form of quantization replaces the need for a wave concept which then appears as a mathematical approach, chosen to avoid the physical concept of an intrinsicc time for any particle, just as we have for its intrinsic mass, spin and electrical charge. to and so are directly related to its frequency, energy and mass. The uncertainty principle and interference relations follow directly from this model, without any physical wave concept. 相似文献
69.
As copper(II) is a common ion in a variety of analytical samples, its effect on the stripping response of lead(II) at bismuth film screen-printed carbon electrode (BFSPCE) was investigated. The study was conducted using a screen-printed three-electrode system (working, counter and reference electrodes), with the carbon-working electrode plated in situ with bismuth film. Copper present at significant concentration level in samples was found to affect the sensitivity of the electrode by reducing the constant current stripping chronopotentiometric (CCSCP) response of lead(II). Recovery of the lead stripping response at the BFSPCE in the presence of copper was obtained when 0.1 mM ferricyanide was added to the test solution. The ferricyanide added circumvents the detrimental effect of copper(II) by selectively masking the copper ions by forming a complex. The analytical utility of the procedure is illustrated by the stripping chronopotentiometric determinations of lead(II) in soil extracts. 相似文献
70.
The electric conduction in the fibrous medium constructed by a homogeneous array of parallel, identical, charged, circular cylinders having an arbitrary zeta potential filled with the solution of a symmetrically charged electrolyte is analytically examined. The thickness of the electric double layers surrounding the dielectric cylinders is assumed to be small relative to the radius of each cylinder and to the gap width between two neighboring cylinders, but the polarization of the mobile ions in the diffuse layers is allowed. The effect of interactions among individual cylinders is taken into explicit account by employing a unit cell model. The appropriate equations of conservation of electrochemical potential energies of ionic species are solved for each cell, in which a cylinder is envisaged to be surrounded by a coaxial cylindrical shell of the fluid solution. Analytical expressions for the effective electric conductivity are obtained in closed forms as functions of the porosity of the fiber matrix and other characteristics of the porous system. Comparisons of the results of the cell model with different conditions at the outer boundary of the cell are made. Under an otherwise identical condition, the electric conductivity in a porous medium composed of an array of parallel cylinders in the transverse direction is smaller than that of a suspension of spheres. The effect of interactions among the cylinders or spheres on the effective conductivity can be quite significant under appropriate conditions. 相似文献