八丁氧基-2,3-萘酞菁铜(Ⅱ)的合成与UV光谱研究

采用分子碎片法合成了5,9,14,18,23,27,32,36-八丁氧基-2,3-萘酞菁铜,利用元素分析、红外及紫外可见光谱进行了表征。配合物的电子吸收光谱表明:新配制的氯仿溶液中萘酞菁铜的Q带H聚集体和单体的吸收峰在758、854nm处,5h后单体和H聚集体的吸收峰基本消失,出现了798和909nm的错位H/J聚集体以及960nm的J聚集体吸收,12h后主要以795nm的H聚集体形式存在。     

Effect of diffusion on lithium intercalation in titanium dioxide

A new model of Li intercalation into rutile and anatase structured titania has been developed from first principles calculations. The model includes both thermodynamic and kinetic effects and explains the observed differences in intercalation behavior and their temperature dependence. The important role of strong local deformations of the lattice and elastic screening of interlithium interactions is demonstrated. In addition, a new phase of LiTiO2 is reported.     

Effect of anion of lithium salt on the property of lithium salt-epoxidized natural rubber polymer electrolytes

Lithium salt, LiX (where X = BF ₄ ^? , I^?, CF₃SO ₃ ^? , COOCF ₃ ^? or ClO ₄ ^? ), was incorporated into epoxidized natural rubber (ENR). Thin films of LiX-ENR polymer electrolytes (PEs) were obtained via solvent casting method. These electrolytes were characterized using SEM/X-mapping, FTIR, differential scanning calorimeter, thermogravimetry analysis, and impedance spectroscopy. The trend in thermal stability and ionic conductivity of LiX-ENR PEs follow LiBF₄ > > LiCF₃SO₃ ~ LiCOOCF₃ > LiI > > LiClO₄. The LiClO₄ hardly dissociates and formed LiClO₄ aggregates within the polymer matrix that resulted in a PE with low thermal stability and low ionic conductivity. The LiCF₃SO₃, LiCOOCF₃, and LiI, however, exert moderate interactions with the ENR, and their respective PEs exhibit moderate ionic conductivity and thermal property. The occurrence of epoxide ring opening and complexation or cross-linking reactions in and between the ENR chains that involve BF ₄ ^? ions have produced a LiBF₄-ENR PE with superior thermal property and ionic conductivity as compared to other PEs studied in this work.     

Effect of electron irradiation on InSb microcrystals

The results of experimental studies of electrophysical properties of heavily doped n-InSb whiskers exposed to electron irradiation (13 MeV, 300 K) are reported. The limiting electrophysical parameters and the problem of the Fermi-level pinning in irradiated InSb are discussed. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 42–45, February, 2006.     

The adsorption of nitrogen dioxide on the Ag(110) surface and formation of a surface nitrate

The adsorption of NO₂ on the Ag(110) surface has been characterized by temperature programmed reaction spectroscopy and high resolution electron energy loss spectroscopy. At 95 K the NO₂ is dimerized to N₂O₄ in a multilayer and a distinct molecular layer, both of which desorb below 200 K. The first adsorption layer contains chemisorbed NO₂ and NO₃, the latter formed by a reaction between NO₂ and its decomposition products. Part of the NO₂ is molecularly chemisorbed via the oxygen atoms with a proposed symmetric bidentate geometry, desorbing at 270 K. Nitrogen dioxide also undergoes partial dissociation to nitrogen and oxygen adatoms. An NO₃ species is formed by the reaction of NO₂ with the oxygen adatoms produced from the partial dissociation of NO₂. The NO₃ is attached to the surface via one oxygen atom and has C_2v symmetry; it decomposes below 500 K. The geometry of both the chemisorbed NO₂ and NO₃ have analogues among inorganic metal complexes.     

EPR of the lithium ion-dangling bond complex in germanium containing dislocations

We have observed a new EPR spectrum in a lithium-diffused germanium crystal N_D-N_A ≈ 10¹³ cm^-3) containing dislocations. The principal g values are 1.917 ± 0.002, 1.896 ± 0.002, and 0.855 ± 0.010 along the axes <1$\text{1}$0>, <11$\text{2}$>, and <111>, plus equivalent sets. As this new spectrum is seen in lieu of the dislocation dangling bond spectrum, we attribute it to a lithium ion- dislocation dangling bond complex.     

EPR Studies on the intermolecular interactions of bis(di-ethanol-dithiocarbamato) copper(II)

The interaction of the title complex, [Cu(EtOH-dtc)₂], with I₂, Br₂ and different metal salts known as electron acceptors is studied in water-ethanol solution. Mixed-ligand complexes Cu(EtOH-dtc)⁺…X^? (X = Cl, Br, I, NO₃) are formed with X^? in the second coordination sphere of the metal ion. Cu(EtOH-dtc)₂ interacts with chloral-hydrate only in the presence of weak Lewis bases and Cu(EtOH-dtc)⁺…Cl^? mixed-ligand complex is formed. The interactions with metal chelates cause the formation of mixed-ligand chelate complexes. Cu(EtOH-dtc)₂ interacts with H₂O₂ and the appearance of mixed-ligand complexes as intermediate products is detected. The final product obtained is CuSO₄. In the presence of O₂ Cu(EtOH-dtc)₂ yielded spectra similar to the above intermediate products. The proposed mechanisms of all studied reactions are discussed on the ground of the recorded spectra.     

Effect of nitrogen and carbon dioxide as fuel impurities on PEM fuel cell performances

Polymer electrolyte membrane (PEM) fuel cells are considered to have the highest power density of all the fuel cells. They operate on hydrogen fuel, which is generally produced by reforming of hydrocarbons, and may contain large amounts of impurities such as carbon dioxide, nitrogen, and trace amounts of carbon monoxide. We studied the effect of dilution of hydrogen gas with carbon dioxide on PEM fuel cells by polarization studies. The polarization curves were different when hydrogen gas was diluted with same quantities of carbon dioxide and with nitrogen. It may be due to carbon monoxide formation by reverse shift reaction and poisoning of anode platinum catalyst. Use of Pt–Ru alloy catalyst was found to suppress the poisoning. The effects of hydrogen gas composition, temperature, current density, and anode catalyst on fuel cell performances were examined in this study.     

EPR spectra of the excited nitrogen state in 6H-SiC

A study is reported of donor EPR spectra in compensated 6H-SiC crystals with donor concentrations (N _D -N _A ) varied from 8×10¹⁷ to 5×10¹⁶ cm^?3, performed within a temperature interval from 77 to 170 K at a frequency of 37 GHz. A second paramagnetic state of nitrogen in silicon carbide has been found to exist, and it is associated with its excited 1S(E) state becoming paramagnetic after thermal ionization of the donor electrons from the 1S(A ₁) to 1S(E) level. The EPR spectrum of nitrogen in the 1S(E) state is a single line with an anisotropic width because of the unresolved hyperfine structure. A light-induced charge transfer between the ground, 1S(A ₁), and excited, 1S(E), nitrogen states has been observed. The valley-orbit splitting and the energy required to ionize donor electrons from the 1S(E) to higher lying excited states have been determined for the cubic nitrogen sites. The parameters of a structural defect, characteristic of n-type 6H-SiC compensated crystals, have been established.     

Resolution enhancement of nitrogen hyperfine patterns in the EPR spectra of Cu(II) complexes: FT Analysis of Cu(II)(His-Gly)2

Fourier analysis of EPR spectra is used to achieve straightforward discrimination between an even or odd number of nitrogen nuclei bound to copper in solution. The method is tested on a copper (II) dipeptide (Cu-HistidylGlycine) complex to confirm the room temperature structural arrangement previously hypothesized by conventional techniques. Any residual uncertainty about ligand coordination around copper in solution is eliminated by the present approach. This simple straightforward method is particularly useful for extracting information from poorly resolved patterns of room temperature EPR spectra.     

压力及杂质氢对金属锂弹性特性的影响

针对六角密堆金属锂16个原子超晶胞(supercell)、填隙一个氢原子的周期单元，采用基于密度泛函理论的平面波-赝势方法，研究了零温条件下压力及填隙氢掺杂对体系弹性性质的影响.结果表明氢掺杂导致体系的体模量增加.常压下掺杂体系的弹性常数C₁₁，C₃₃，C₆₆和C₁₂高于单质体系，剪切模量C₄₄有所下降，而C₁₃则与单质体系持平.压力作用下C₁₁，C₃₃和C₆₆一直大于单质体系，但C₁₂的值低于单质体系.在2GPa—4GPa压力区间内，弹性常数C₁₃呈反常变化，小于单质体系；在高压区掺杂体系的C₄₄和C₁₃则高于单质体系的相应量值，压力导致掺杂体系和单质体系之间剪切模的偏离加剧.掺杂体系在压力作用下依然保持压缩模的各向同性，具有和单质体系相似的特性. 关键词： 第一性原理 压力效应 弹性常数 金属锂     

The chaotic property in the autoionization of Rydberg lithium atom

This paper presents theoretical computations of the ionization rate of Rydberg lithium atom above the classical ionization threshold using semiclassical approximation. The yielded random pulse trains of the escape electrons are recorded as a function of emission time such that they can be related to the terms of the recurrence periods of the photoabsorption. This fact illustrates that it is ionic core scattering processes which give rise to chaos in autoionization dynamics and this is verified by comparison of our results with the hydrogen atom situation. In order to reveal the chaotic properties in detail, the sensitive dependence of the ionization rate upon the scaled energy is discussed for different scaled energies. This approach provides a simple explanation for the chaotic character in autoionization decay of Rydberg alkali-metal atoms.     

EPR of Mn2+ and Eu2+ ions in the bulk and on the surface of AIBVII type single- and microcrystals

A new dimensional effect is investigated. It consists in a change of the microstructure of bulk impurity defects after a decrease in the crystal size. The results of studying the changes in the defect structure in (NaCl, KCl, LiF):Mn²⁺ and (NaCl, KCl, KBr):Eu²⁺ by electronic paramagnetic resonance (EPR) are presented. Samples of different sizes and nature are investigated: bulk-doped single crystals of large sizes; bulk-doped crystals of small sizes; powder samples of various degree of dispersity, which are obtained by crushing the samples of large sizes; and samples with direct doping of the surface. The spectra of three types are measured: the spectra of single crystals; the spectra of the powders with the sizes of the particlesd ≥ 1 mm; the spectra of the powders withd ≤ 3 μn (analogous spectra have the surface-doped samples). Considerable change in the EPR spectra as the samples are continuously crushed is due to the change of the paramagnetic center (PC) structure. In the case of bulk-doped single crystals the paramagnetic ion compensator is in the nearest cation coordination sphere. When the deformation caused by the surface region becomes large enough in the vicinity of PC, detachment and removal of the compensator from the impurity ion take place. As a result, the local symmetry of the PC is changed and is revealed in the EPR spectra.     

Effects of nitrogen on the carbon anode of a lithium secondary battery

Nitrogen-containing carbons have been made from different polymer precursors at 600°C. Their composition and structure have been studied by chemical analysis, X-ray powder diffraction and X-ray photoelectron spectroscopy. These results show that this kind of carbon is disordered, and nitrogen exists as two kinds of forms in the polymeric carbons: graphene nitrogen (N_1s binding energy 398.5 eV) and conjugated nitrogen (N_1s binding energy 400.2 eV). The discharge and charge process suggests that these two kinds of nitrogen are bonded satisfactorily and could not result in irreversible reaction with Li. The increase of reversible capacity mainly results from the graphene nitrogen, and the higher the content of nitrogen, the higher the charge capacity. Part of the irreversible capacity is derived from the formed lithium carbide and lithium atoms which are intercalated and could not be deintercalated.     

Effect of annealing on structural and optical properties of lead tungstate microcrystals

Shuttle-like lead tungstate (PbWO₄) microcrystals are synthesized at room temperature using the precipitation method with the cetyltrimethyl ammonium bromide. Results from both the X-ray diffraction and the scanning electron microscopy show that the lattice distortions of the PbWO₄ microcrystals are reduced significantly when the annealing temperature is increased to 873 K. The result from the ultraviolet-visible diffuse reflectance spectroscopy shows that the exciton absorption appears in the sample annealed at 673 K. The self-trapped exciton luminescence due to the Jahn-Teller effect is also observed in the blue band. The interstitial oxygen ions in the WO₄^2- groups are mainly resposible for the enhancement effect of the green luminescence of the annealed samples. The above results are supported by the spectrum analysis of the as-grown and the post-annealed samples using the X-ray photoelectron spectroscopy.     

High-field EPR on the cyclic spin cluster Fe6(tea)6

The eigenstates of the antiferromagnetic spin cluster Fe₆(tea)₆ are studied by electron paramagnetic resonance spectroscopy at 9.5 and 94 GHz in order to characterize the interactions which are important for the magnetic properties of the molecule. Experimental results could be obtained for the first excited spin states withS= 1, 2, 3 and 4. This enables a very accurate and detailed analysis of the intramolecular interactions. It turns out that the magnetic properties of Fe₆(tea)₆ are determined by the isotropic exchange (J/k_B = ?31.5 K), the ligand-field interaction of the Fe^III ions and the dipolar interaction. Other kinds of anisotropic interactions are of minor importance.     

EPR of the first Fe(III)-containing spin-crossover metallomesogens

The low-spin (LS) to high-spin (HS) transition in two mesogenic Fe(III) complexes with alkyloxysalicyliden-N^′-ethyl-N-ethylendiamine as ligands is studied by electron paramagnetic resonance (EPR). The symmetrization of the crystal field around the Fe(III) ion under first heating of a polycrystalline sample from the room temperature was observed in the spectra of HS complexes. The line narrowing (from 45 to 15 mT) under the crystal-smectic phase transition is explained by the strengthening of the intermolecular exchange interaction, as a result of the structural reorganization of layers in the smectic phase. A feature of both mesogenic spin-transition systemsis an unusual field-induced spin instability which leads to the hysteresis of the HS-LS composition. This instability is detected by EPR and magnetic susceptibility methods. The alignment of systems by magnetic field in the mesophase and a complete or partial orientational order under cooling the mesophase to the glass state are the main reason for this hysteresis. The influence of EPR-silent LS complexes reveals itself in the line broadening of HS compounds’ when the temperature is lowered from 220 K.