水溶液中4种杂环化合物的荧光光谱的理论研究

采用量子化学半经验方法RHF/AM1对4种六元杂环化合物进行水溶液中的构型优化, 经振动分析, 未出现虚频率。在此基础上用RHF/CIS方法分别计算了它们的荧光光谱, 并与其气相计算的结果进行了对比, 在水溶液中的计算结果能更好地符合实验值。     

几种稠环芳烃有机EL材料性能的量子化学理论研究

采用量子化学半经验方法（ＲＨＦ／ＰＭ３）对几种稠环芳烃化合物电致发光（ＥＬ）材料的性质进行了理论研究。利用能量梯度法优化构型,对各优化的构型作振动分析,均未出现虚频率。在此基础上,采用ＲＨＦ／ＣＩＳ方法计算其电子光谱。并给出了化合物ＥＬ１,ＥＬ２电子光谱的最大波长λ与ＣＩＳ组态之间的关系。所有计算结果与实验值基本吻合。     

Polypyrrole electrodeposition on inorganic semiconductors CuInSe2 and CuInS2 for photovoltaic applications

Thin polypyrrole (PPy) layers with an average thickness of about 0.5 μm were deposited, using potentiostatic and galvanostatic techniques, on CuInSe₂ (CISe) structures prepared electrochemically on glass/ITO substrates and on CuInS₂ (CIS) structures fabricated on Cu tape substrates. The polymer layer of p-type is considered as an alternative to the traditional buffer layer and window layer in the conventional cell structure. The deposition proceeded from an aqueous solution containing sodium naphthalene-2-sulfonate as a dopant. In order to prepare stable PPy films of high quality with a good adherence to the surface of inorganic semiconductors CIS and CISe, the optimal concentrations of reagents, current densities and electrodepositing potentials were selected experimentally. Electrochemical polymerization of pyrrole to PPy on CIS surfaces is faster under white light irradiation and the polymerisation starts at lower potential than in the dark. Significant photovoltage and photocurrent of the fabricated CISe/PPy and CIS/PPy structures have been observed under standard white light illumination.     

几种多环芳烃化合物EL材料性质的量子化学研究

采用从头算方法（ＲＨＦ／４－３１Ｇ）和半经验方法ＡＭ、ＰＭ３对几种多环芳烃化合物电致发光（ＥＬ）材料的性质进行了理论研究。并对三联苯作了构象分析，找出能量最低的构象，即两侧苯环分别城外各扭转４１．６°±０．５°，对各优化后的构型作振杂质镁未出现虚频率，在此基础上，采用ＲＨＦ／ＣＩＳ方法计算其电子光谱，并给出了化合物Ｅ２，Ｅ３电子光谱的波长λ与ＣＩＳ的组态数之间的民有计算结果与实验值基本吻合。     

Electronic structures of permethyloligosilane radical cations at the ground and low-lying excited states

The electronic structures at the ground and low-lying excited states of permethyloligosilane radical cations, Si_n(CH₃)_2n+2⁺ (n = 4-7), have been investigated using DFT and ab initio calculations. The calculations showed that positive charge (hole) is delocalized along the Si-Si main chain at the ground and first excited states. On the other hand, the hole is transferred to the methyl side-chain at the second and higher excited states. From these results, it was concluded that hole can move along the Si-Si main chain at thermal conditions. Also, it was predicted that intermolecular hole hopping takes place by photo-irradiation to the permethyloligosilane radical cation. The mechanism of hole transfer was discussed on the basis of the results.     

Comparison of different sampling heads applied for investigation of welding fume

Welding fume samples were collected in two Hungarian welding plants, where different types of steels were welded with metal active gas (MAG) welding. Welding fumes were sampled with “fixed point” and personal sampling techniques applying different sampling heads: Institute of Occupational Medicine (IOM) sampler and conical inhalable sampler (CIS) for the inhalable aerosol fraction and the Higgins-Dewell (HD) cyclone for the respirable fraction. When sampled, the welding fume samples were digested with the mixture of nitric acid and hydrogen peroxide in a closed vessel microwave digestion system. The Cr, Mn, Ni and Co contents of the solutions were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). Iron was analysed only by the ICP-AES method. Metal concentrations of the workplace air were calculated for the three samplers, and the results were compared to each other. The differences of the metal concentrations determined by the different inhalable sampling heads, which were paired during the sampling, proved not to be significant. Therefore, the IOM and CIS heads can be equally used for the sampling of welding fume. Finally, the distributions of metals were determined between the inhalable and respirable fractions. Metal concentrations in the respirable aerosol fraction were 57-98% of the concentrations in the inhalable fraction. These high rates of metals in the respirable aerosol call the attention to the increased health risk of the welding fume.     

Size-Nonextensive Contributions in Singles-Only CI

The size-nonextensivity (SNE) of the configuration interaction scheme with single excitations only (CIS) is discussed. On the basis of model considerations the method is explicitly shown to give energies which have wrong dependence on the number of particles. The same model of a multimer of N noninteracting subsystems, each in the same singly excited state, is analyzed in terms of the many-body perturbation theory expansion. This suggests new computational schemes which will be either completely free of the size-nonextensive contributions or may have them removed a posteriori. The extension of the perturbation scheme leads to the singles-only coupled cluster approach with a singly excited reference function. The consequences of the present model study for computational methods for inexpensive calculations of the electronic spectra of molecules, are investigated.     

三种偶氮化合物的荧光光谱研究

近年来 ,一些重要的有机染料探针在生物大分子光度分析、荧光分析和共振光散射分析方面得到了日益广泛地应用[1,2 ] ,深入研究这些有机染料的结构和光谱特性 ,探讨这些有机染料与生物大分子之间的作用 ,对于筛选性能优良的分子光谱探针 ,设计更加灵敏简便的分子光谱检测器件 ,是现代分析化学十分重要的课题。本文测定了偶氮胂Ⅱ (Ａｒｓｅｎａｚｏ)、铬黑Ｔ(ＥｒｉｏｃｈｒｏｍｅｂｌａｃｋＴ)、铬蓝黑 (ＥｒｉｏｃｈｒｏｍｅｂｌｕｅｂｌａｃｋＲ)等 3种化合物的荧光光谱 ,并用量子化学半经验方法ＡＭ1和ＰＭ3对3种化合物分子进行包括构型…     

Chiral recognition by enantioselective liquid chromatography: Mechanisms and modern chiral stationary phases

An overview of the state-of-the-art in LC enantiomer separation is presented. This tutorial review is mainly focused on mechanisms of chiral recognition and enantiomer distinction of popular chiral selectors and corresponding chiral stationary phases including discussions of thermodynamics, additivity principle of binding increments, site-selective thermodynamics, extrathermodynamic approaches, methods employed for the investigation of dominating intermolecular interactions and complex structures such as spectroscopic methods (IR, NMR), X-ray diffraction and computational methods. Modern chiral stationary phases are discussed with particular focus on those that are commercially available and broadly used. It is attempted to provide the reader with vivid images of molecular recognition mechanisms of selected chiral selector–selectand pairs on basis of solid-state X-ray crystal structures and simulated computer models, respectively. Such snapshot images illustrated in this communication unfortunately cannot account for the molecular dynamics of the real world, but are supposed to be helpful for the understanding. The exploding number of papers about applications of various chiral stationary phases in numerous fields of enantiomer separations is not covered systematically.