Chemical maps of patterned samples by microline‐imaging laser‐induced plasma spectrometry

The potential of a microline‐imaging laser‐induced plasma spectrometry (LIPS) system for surface and depth analysis of heterogeneous solid samples in air at atmospheric pressure has been demonstrated. A pulsed Nd : YAG laser beam operating at 532 nm, with a homogeneous energy distribution (flat top laser), was used to generate a microline plasma on the sample surface. Subsequent light from the microline plasma was resolved spectrally and spatially and detected with an imaging spectrograph and an intensified charged‐coupled device detector. A patterned metal sample was chosen as the most appropriate for this study. Three‐dimensional chemical maps of Ni and Cu from the edge connectors of a printed circuit board have been obtained. With this experimental configuration, the lateral resolution (limited by crater width) was 42 µm and the spatial resolution along the spectrometer slit was 17.4 µm. The results illustrate the capability of microline imaging for fast mapping of large‐area samples and for depth profiling purposes. Copyright © 2003 John Wiley & Sons, Ltd.     

Advanced kinetic tools for the evaluation of decomposition reactions

Summary An advanced kinetic study on the thermal behaviour of pyrotechnic ignition mixtures has been carried out by differential scanning calorimetry using different B/KNO3 mixtures (50:50, 30:70, 20:80) as a model reaction. The experimental conditions applied (isochoric conditions/closed crucibles and isobaric conditions/open crucibles) as well as the composition of the mixtures noticeably influences the relative thermal stabilities of the energetic materials. The kinetic study focused on the prediction of the thermal stability of the different mixtures both in extended temperature ranges and under temperature conditions at which ordinary investigation would be very difficult. Using advanced numerical tools [1], thermal ageing and influence of the complex thermal environment on the heat accumulation conditions were computed. This can be done for any surrounding temperature profile such as isothermal, non-isothermal, stepwise, modulated, shock, adiabatic conditions and additionally for temperature profiles reflecting real atmospheric temperature changes (yearly temperature profiles of different climates with daily minimal and maximal fluctuations). Applications of accurate decomposition kinetics enabled the determination of the time to maximum rate under adiabatic conditions (TMR_ad) with a precision given by the confidence interval of the predictions. This analysis can then be applied for the examination of the effects of the surrounding temperature for safe storage or transportation conditions (e.g. determination of the safe transport or storage temperatures).     

Novel composite anode materials for lithium ion batteries with low sensitivity towards humidity

Graphitic anode materials for lithium ion batteries processed under high humidity conditions show severe performance losses. The sensitivity of these materials towards humidity can be significantly reduced by adsorbing metal ions like silver or copper ions, with subsequent heat treatment of these composites. Results of X-ray photoelectron spectroscopy, high-resolution electron microscopy, thermogravimetry, and differential thermal analysis indicate that the deposited metals exist in metallic and carbide, M_xC (M=Cu or Ag), forms. They remove or cover (i.e. deactivate) active hydrophilic sites at the surface of the graphite. These composites absorb less water during processing. The electrochemical performance, including reversible capacity, coulombic efficiency in the first cycle, and cycling behavior, is markedly improved. This approach provides a potentially powerful method to manufacture lithium ion batteries under less demanding conditions.Presented at the 3rd International Meeting on Advanced Batteries and Accumulators, 16–20 June 2002, Brno, Czech Republic     

Composition and thermal stability of SiO2-based hybrid materials TEOS-MTEOS system

Hybrid materials with different amounts of organics permanently bound on the inorganic network obtained in the TEOS-MTEOS (tetraethoxysilan-methyltriethoxysilan) system are used for obtaining coatings with different optical and mechanical properties. To study the thermal stability of the mentioned materials, compositions with different molar ratios of the precursors were prepared. The influence of the solvent and water amounts on the gelation process was also investigated. The gels obtained were characterised by IR spectrometry and their decomposition temperatures were determined by DTA/TG. Thermal stability of the gels is rather influenced by their composition than the conditions of the gelation process. This revised version was published online in July 2006 with corrections to the Cover Date.     

Solution Stoichiometry Control for Pure LiLaMo2O8Phases in Sol-Gel Preparation

The hydrolysis of solutions, containing either LiMo₂O₄(OPr ⁱ )₅( ⁱ PrOH) and “La(OPr ⁱ )₃” or LiOPr ⁱ and La₂Mo₄O₈(OPr ⁱ )₁₄ in 1∶1 ratio, in toluene or ⁱ PrOH, by water solutions in isopropanol, leads to formation of monolythic gels. The latter can be converted by drying and heat treatment at 600°C into a fine powder of pure α-LiLaMo₂O₈ phase, which is transformed into β-LiLaMo₂O₈ powder by annealing at 800°C. The sintering of the pellets pressed under 4 bar pressure of α-LiLaMo₂O₈ powder at 800°C for 2 h converts them into pieces of β-LiLaMo₂O₈ transparent ceramics, thus providing a route to LiLnMo₂O₈ laser waveguide materials.     

Immobilization of copper in organic-inorganic hybrid materials: a highly efficient and reusable catalyst for the Ullmann diaryl etherification

The immobilization of copper in organic-inorganic hybrid materials catalyzing the Ullmann reaction has been described. Phenols reacted with aryl iodides, aryl bromides and aryl chlorides smoothly in the presence of a 3-(2-aminoethylamino)propyl functionalized silica gel immobilized copper catalyst. The protocol involved the use of DMSO as the solvent, and potassium fluoride as the base. The reactions generated the corresponding cross-coupling products in good to excellent yields. Furthermore, the silica-supported copper could be recovered and recycled by a simple filtration of the reaction solution and used for 10 consecutive trials without loss of its reactivity.     

星状四芳胺类空穴传输材料的合成

有机电致发光器件 (ＯＥＬＤ)是继阴极射线管平板显示器 (ＣＲＴ)和液晶显示器 (ＬＣＤ)之后的第三代平板显示器。它具有主动发光、驱动电压低(2伏左右 )、发光亮度高 (1 3 0 0 0ｃｄ ｍ2 以上 ) ,无软Ｘ 射线污染 ,响应速度快 (1 0 -6 ～ 1 0 -8秒 )等优点。从 1 987年美藉华人邓清云等提出多层结构的ＯＥＬＤ的器件结构以来的十多年间 ,ＯＥＬＤ以及其材料的研究已成为显示技术以及显示材料等方面的研究热点 ,发展很快[1～ 3] 。在 1 999年日本先锋公司已开发出了单色的汽车用ＯＥＬ平板显示器商品 ,今年东芝公司又开发出了 2 .7英寸的彩…     

Traceability and analytical chemistry

 The basic concepts of traceability as they are defined by the Comité Consultatif pour la Cluantité de Matière are contrasted with the practical exploitation in chemical analysis. The applicability of traceability concepts are tested for their practical applicability on four different analytical methodologies, neutron activation analysis, plasma mass spectrometry, beam microscopical analysis and speciation analysis of organometallic compounds. Received: 31 March 1998 · Accepted: 6 June 1998     

The determination of adsorbable organically bound halogens (AOX) in soil: interlaboratory comparisons and reference materials

The interlaboratory variability in the quantification of adsorbable organically bound halogens (AOX) in industrially contaminated soil is presented. Three consecutive rounds of a proficiency testing scheme, in which between 88 and 119 routine laboratories participated, yielded relative reproducibility standard deviations between 7 and 20% at AOX contents between 10.9 and 268 mg kg⁻¹. Nineteen laboratories with established proficiency were invited to participate in the certification of the AOX content in three soil reference materials meant for the internal quality control in analytical laboratories. The certified values are (1349 ± 59) mg kg⁻¹, (80 ± 7) mg kg⁻¹ and (102 ± 8) mg kg⁻¹, respectively.     

Heterogeneous oxidation of pyrimidine and alkyl thioethers in ionic liquids over mesoporous Ti or Ti/Ge catalysts

Heterogeneous catalytic oxidation of a series of thioethers (2-thiomethylpyrimidine, 2-thiomethyl-4,6-dimethyl-pyrimidine, 2-thiobenzylpyrimidine, 2-thiobenzyl-4,6-dimethylpyrimidine, thioanisole, and n-heptyl methyl sulfide) was performed in ionic liquids by using MCM-41 and UVM-type mesoporous catalysts containing Ti, or Ti and Ge. A range of triflate, tetrafluoroborate, trifluoroacetate, lactate and bis(trifluoromethanesulfonyl)imide-based ionic liquids were used. The oxidations were carried out by using anhydrous hydrogen peroxide or the urea-hydrogen peroxide adduct and showed that ionic liquids are very effective solvents, achieving greater reactivity and selectivity than reactions performed in dioxane. The effects of halide and acid impurities on the reactions were also investigated. Recycling experiments on catalysts were carried out in order to evaluate Ti leaching and its effect on activity and selectivity.