On Conformal Invariants Built from Spinor Fields

By means of a conformal covariant differentiation process we construct generating systems for conformally invariant symmetric (r, s)–spinors in an arbitrary curved space–time. Extending this method to conformally invariant linear differential operators acting on symmetric spinor fields some classes of such operators are derived.     

An infrared study of the effects of hydration on cation‐loaded nafion thin films

We explore the effects of hydration on the vibrational spectra of cation‐exchanged Nafion thin films. In addition to the initial H⁺ form of the membrane, the cations selected for study include: Na⁺, NH, tetramethylammonium, tetrabutylammonium, hexadecyltrimethylammonium, and tris(2,2′‐bipyridine)osmium(II). A flow cell is used to follow the changes occurring in a 1000‐Å film in response to variations in the humidity of a nitrogen purge gas flowing through the cell. The structural changes occurring due to the binding of water to these cation‐exchanged membranes is followed across a broad range of water contents with IR difference spectroscopy. Our results demonstrate a complex role for water in mediating the polyanion–cation interactions. Side‐chain reconstructions may play an important role in the ion‐binding and transport properties of the ionomer domains. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1512–1520, 2000     

Synthesis and characterization of semifluorinated polymers and block copolymers

The goal of the investigation presented here was to evaluate the influence of semifluorinated side chains on the bulk structure and the surface properties of polysulfones with different chain structure. Thus, segmented block copolymers consisting of polysulfone and semifluorinated aromatic polyester segments as well as polysulfones having semifluorinated side chains randomly distributed over the polymer backbone were synthesized and characterized. Oxydecylperfluorodecyl side chains were used because of their strong tendency for self-organization. The influence of the chain architecture on the self-organization as well as on the surface properties, particularly the wetting behavior, was examined. It could be shown that despite of the higher self-organizing tendency of block copolymers the surface properties of both polymer types are comparable and depend only on the concentration of side chains.     

Efficient synthesis of substituted 1‐dimethylamino or 1‐methylthio but‐3‐enylidene‐bis‐phosphonates,via the [2,3]‐sigmatropic rearrangement of related transient ammonium or sulfonium ylides

New variously substituted 1‐dimethylamino or 1‐methylthio but‐3‐enylidene‐bis‐phosphonates have been prepared from readily availableα‐dimethylamino or α‐methylthio methylene‐bis‐phosphonates by postulated [2,3]‐Wittig rearrangements of the corresponding N‐ or S‐allylic intermediate ylides. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 281–289, 1999     

icMRCI+Q理论研究CF离子12个-S态和23个?态的光谱性质

采用考虑Davidson修正的内收缩多参考组态相互作用(icMRCI+Q)方法结合相关一致基组aug-ccpV5Z和aug-cc-pV6Z计算了CF~+离子第一离解极限C~+(~2p_u)+F(~2P_u)对应的12个∧-S态(X~l∑~+,a~3∏,1~3∑~+,1~3Δ,1~1∑~-,1~1∑~-,1~3∑~-,2~1∑~+,1~1∏,2~3∏,2~1∏和2~3∑~+)所产生的23个Ω态的势能曲线.计算中考虑了旋轨耦合效应、核价相关和标量相对论修正以及将参考能和相关能分别外推至完全基组极限.基于得到的势能曲线,获得了束缚和准束缚的9个∧-S态和16个Ω态的光谱常数,并且X~1∑~+,a~3∏~(势阱一)∧-S态的光谱常数与已有的实验结果非常符合.此外,计算了CF自由基X~2∏态到CF~+离子束缚和准束缚的9个∧-S态的垂直电离势和绝热电离势,并且CF~+(X~1∑~+)←CF(X~2∏)和CF~+(a~3∏(势阱一))←CF(X~2∏)的垂直电离势和绝热电离势与相应的实验结果也非常符合.由a~3∏,1~1∏态和其他激发∧-S态势能曲线的交叉现象,借助于计算的旋轨耦合矩阵元,分析了a~3∏~(势阱一),1~1∏~(势阱一)和2~1∑~+态的预解离机理.计算的23个Ω态离解极限处的相对能量与实验结果十分吻合.最后计算了(2)0+~(势阱一)(v'=0-5),(1)1~(势阱一)(v'=0-5)和(2)1~(势阱一)(v'=0)到X0~+态跃迁的Franck-Condon因子和辐射寿命.     

两相催化体系中长链烯烃氢甲酰化反应研究——反应初期的界面化学特征

从界面化学的角度研究了水／有机物两相体系中ＲｈＣｌ（ＣＯ）（ＴＰＰＴＳ）２－ＣＴＡＢ催化１－十二碳烯氢甲酰化反应初期的界面特征。结果表明,催化剂及过量配体的加入,使ＣＴＡＢ的ＣＭＣ降低。样品的光散射及显微照片表明,在ＣＴＡＢ浓度为２．７～６ｍｍｏｌ／ｄｍ＾３范围内,体系中存在着ＣＴＡＢ单体／胶束－Ｏ／Ｗ型乳认间的平衡,在较高ＣＴＡＢ浓度下可能形成Ｏ／Ｗ型微乳;胶束及Ｏ／Ｗ型乳状液滴界面呈负电性,证     

Particle-depletion dynamics in axisymmetric thermocapillary flows

The European Physical Journal Special Topics - The removal of suspended particles from the interior of a thermocapillary liquid bridge via a finite-particle-size effect restricting the particle...     

Intrinsic relaxation rates of polarized Cs vapor in miniaturized cells

The intrinsic relaxation rates of the vector magnetization of cesium vapor enclosed in microfabricated atomic magnetometer cells are investigated. Two methods—the optically detected magnetic resonance and the ground-state Hanle effect—are used to carry out automated measurements in dependence on cell temperature and nitrogen buffer gas pressure. The experimental results are compared with expected contributions of the different relaxation processes and in this way allow the discrimination between them to help further optimization of cell design. The methods are compared in terms of basic features, data quality, and practical applicability.