Si(CH3)2Cl2分子的电离电势和化学键能的测定

有机硅化合物是半导体工业中产生硅元件的基本原料和有机合成中的重要试剂，是多年来大家研究较多的分子体系之一．本文报导了用同步辐射加速器产生的真空紫外光，电离St（CH3hCI。分子．在50－120n－m波长范围内，测量了各种离子产物与真空紫外光波长的关系，推算得它的绝热电离电势和离子中几个化学键的键能．1实验装置和方法本工作在国家同步辐射实验室光化学实验站进行．进行分子真空紫外光电离研究的实验系统已在文献山中详细描述．同步辐射加速器产生的真空紫外光波长用Ne气的电离势标定，其误差＜士0－Inln．单色仪的分辨率为河凸…     

On the Existence and Hydrolytic Stability of Titanosiloxane Bonds in the System: Glycidoxypropyltrimethoxysilane-Water-Titaniumtetraethoxide

Heterometal materials based on glycidoxypropyltrialkoxysilane and titaniumalkoxide are used for optical applications and require a high homogeneity on the molecular level. The presence of heterometal titanosiloxanes, their distribution and hydrolytic stability should influence the homogeneity of these materials. 29Si and 17O NMR spectroscopy has been used to investigate sols with molar ratios Si : Ti = 1 and H2O : OR (H) = 0.5 – 2.0 and their gels after heat treatment at 130°C. The presence of Si—O—Ti bonds in sols with a low water content (H < 0.2) and in the corresponding gels was identified by the high-field shift of the 29Si NMR signals of T1 and T2 units of up to 2–3 ppm compared to corresponding signals of homo-condensed Si—O—Si bonds. The existence of Si—O—Ti bonds in the sols is supported by 17O NMR spectra which show a characteristic signal around 340 ppm. A cleavage of the Si—O—Ti bonds occurs with increasing water/OR ratio in the sols. The cleavage of the heterometal bonds and the building up of homo-condensed species leads to a separation into areas with predominantly Ti—O—Ti and Si—O—Si bonds resulting in a decreased molecular homogeneity of the materials.     

R?ntgenspektrometrische Bestimmung von Eisen-55 in Luftstaub- und Niederschlagsproben

Zusammenfassung Eisen-55 wurde in Neuherberg bei München seit März 1970 in monatlich gesammelten Luftstaubproben und seit Januar 1971 in Monatsniederschlagsproben bestimmt. Nach dem Veraschen der Proben wurde Eisen durch Extraktion' mit Di-iso-propyläther abgetrennt. Zur weiteren Entfernung störender Radionuklide des Fallouts wurde eine Ionenaustauschertrennung angeschlossen. Nach der elektrolytischen Abscheidung des Eisens auf Kupferplättchen wurden die Röntgenspektren mit einem Proportionalzähler sowie einem Si(Li)-Detektor aufgenommen.Die mittlere spezifische Luftaktivität betrug in Neuherberg 1,0 fCi/m³ im Jahr 1970 (ab März), 1,2 fCi/m³ im Jahr 1971 und 0,36 fCi/m³ im Jahr 1972. Die dem Boden durch den Niederschlag zugeführte Aktivität wurde zu 697 pCi/m² · Jahr für 1971 und 178 pCi/m² · Jahr für 1972 bestimmt.Vortrag anläßlich der Tagung Spurenanalyse, 2. bis 5. April 1973 in Erlangen.     

XRD and Si MAS-NMR spectroscopy across the β-Lu2Si2O7-β-Y2Si2O7 solid solution

Samples in the system Lu_2−xY_xSi₂O₇ (0?x?2) have been synthesized following the sol-gel method and calcined to 1300 °C, a temperature at which the β-polymorph is known to be the stable phase for the end-members Lu₂Si₂O₇ and Y₂Si₂O₇. The XRD patterns of all the compositions studied are compatible with the structure of the β-polymorph. Unit cell parameters are calculated as a function of composition from XRD patterns. They show a linear change with increasing Y content, which indicates a solid solubility of β-Y₂Si₂O₇ in β-Lu₂Si₂O₇ at 1300 °C. ²⁹Si MAS NMR spectra of the different members of the system agree with the XRD results, showing a linear decrease of the ²⁹Si chemical shift with increasing Y content. Finally, a correlation reported in the literature to predict ²⁹Si chemical shifts in silicates is applied here to obtain the theoretical variation in ²⁹Si chemical shift values in the system Lu₂Si₂O₇-Y₂Si₂O₇ and the results compare favorably with the values obtained experimentally.     

A new method for the synthesis of silicon-and germanium-containing 2-acetylfurans and 2-acetylthiophenes

A new method was developed for the synthesis of silicon-and germanium-containing acetylfurans and acetylthiophene by metallation of 2-acetylfuran or 2-acetylthiophene with n-BuLi at low temperature after protection of the carbonyl group with lithium N-methylpiperazide and reaction of the lithium derivative with various trialkyl-, alkylphenyl-, and cycloalkylchlorosilanes or trialkylchloro(bromo)germanes. The cytotoxic activity of the new compounds was studied, and it was established that the silicon-and germanium-containing acetylfurans and acetylthiophenes are substances with low toxicity (LD₅₀ 312->2000 mg/kg) and have low cytotoxicity toward HT-1080 and MG-22A tumor cells. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 192–199, February, 2007.     

Fe—Silicalite—2催化剂表面CO2加氢反应性能的研究

研究了Ｆｅ／Ｓｉｌｉｃａｌｉｔｅ－２催化剂ＣＯ２加氢低碳烯烃反应性能，利用ＣＯ２－ＴＰＤ，ＣＯ２／Ｈ２－ＴＰＳＲ和ＣＯ／Ｈ２－ＴＰＳＲ表征手段，考察了铁含量及ＭｎＯ助剂对Ｆｅ／Ｓｉｌｉｃａｌｉｔｅ－２催化剂ＣＯ２吸附脱附及加氢反应性能的影响，表明随铁含量增加可提高催化剂对ＣＯ２的吸附能力，有利于提高ＣＯ２加氢反应的转化率。     

Synthesis and Characterization of Base‐catalyzed Phenyl Modified PDMS/PHMS Copolymers

A series of phenyl modified polydimethylsiloxane (PDMS) / polyhydrogenmethylsiloxane (PHMS) random copolymers containing both internal Si‐H and terminal SiH₂ and T (MeSiO_3/2) units was synthesized in one step through n‐BuLi‐catalyzed ring‐opening polymerization of cyclic comonomers and characterized by GPC, IR and ¹H and ²⁹Si NMR. Sequential microstructures of these copolymers were determined by ²⁹Si‐NMR spectroscopy. Epoxy‐modified polysiloxanes were prepared and used as comparable standards for the assignment of the NMR spectra. A hydride‐transfer mechanism has been proposed to account for the formation of terminal Si‐H and T group. Detailed sequential analyses and chemical shifts of ²⁹Si‐NMR for various siloxane units are reported for the first time.     

Cd2Ge7O16中Tb的长余辉发光特性

本文研究了Cd₂Ge₇O₁₆∶Tb³⁺材料的发光及其长余辉性质。指出Tb³⁺的发光是该离子的 ⁵D₃- ⁷D_J、 ⁵D₄- ⁷D_J两种跃迁产生的；随着掺杂浓度的增加 ⁵D₄- ⁷D_J跃迁增强，发光颜色由蓝变绿。并把该材料的长余辉性质归结为基质结构中有电子陷阱和空穴陷阱。提出余辉机理模型。     

Cathodoluminescence Depth Profiling in SiO2:Ge Layers

 For investigation of the luminescent center profile cathodoluminescence measurements are used under variation of the primary electron energy E ₀ = 2…30 keV. Applying a constant incident power regime (E ₀·I ₀ = const), the depth profiles of luminescent centers are deduced from the range of the electron energy transfer profiles dE/dx. Thermally grown SiO₂ layers of thickness d = 500 nm have been implanted by Ge⁺-ions of energy 350 keV and doses (0.5–5)10¹⁶ ions/cm². Thus Ge profiles with a concentration maximum of (0.4 – 4) at% at the depth of d_m≅240 nm are expected. Afterwards the layers have been partially annealed up to T _a = 1100 °C for one hour in dry nitrogen. After thermal annealing, not only the typical violet luminescence (λ = 400 nm) of the Ge centers is strongly increased but also the luminescent center profiles are shifted from about 250 nm to 170 nm depth towards the surface. This process should be described by Ge diffusion processes, precipitation and finally Ge nanocluster formation. Additionally, a Ge surface layer is piled-up extending to a depth of roughly 25 nm.     

A sequential injection spectrophotometric method for the determination of penicillamine in pharmaceutical products by complexation with iron(III) in acidic media

A simple, robust and sensitive sequential injection spectrophotometric method for the assay of penicillamine (PA) in pharmaceutical formulations is developed. The method was based on the complex formation when PA is reacted with iron(III) solution in hydrochloric acid media. The deep blue colored PA-iron(III) complex produced is monitored at a maximum wavelength of 600 nm. A five level orthogonal array design coupled to genetic algorithm was employed to obtain the optimum experimental conditions for the determination of PA using peak absorbance as the measure of the system's performance criterion. A linear dynamic range for the determination of PA of 25-300 ppm was obtained with a sampling frequency of 50 h⁻¹ and a relative standard deviation of less than 0.98%. The method was successfully applied to the determination of PA in pharmaceutical formulations.