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61.
叙述了同步辐射白光全反射X射线荧光分析的实验装置,给出了几种标准物质TXRF实验的检出限,并对实验结果进行了讨论。 相似文献
62.
Gejihu De Weiping Qin Jisen Zhang Yan Wang Chunyan Cao Yang Cui 《Journal of solid state chemistry》2006,179(3):955-958
In this work, we used the hydrothermal method to synthesize Eu3+ ion-doped cubic BaF2 nanorods, which is a luminescent material. The clubbed structures were well crystallized and exhibited face-centred cubic structures, as indicated by powder X-ray diffraction, scanning electron microscopy, electron diffraction, and transmission electron microscopy. The luminescent properties were studied, and local symmetry surrounding Eu3+ ions and electronic transition processes included. The results indicated that Eu3+ occupied only one C4ν site in nanorods. 相似文献
63.
We study the phase diagram and orientational ordering of guest liquid crystalline (LC) rods immersed in a quenched host made of a liquid crystalline polymer (LCP) matrix with mobile side chains. The LCP matrix lies below the glass transition of the polymer backbone. The side chains are mobile and can align to the guest rod molecules in a plane normal to the local LCP chain contour. A field theoretic formulation for this system is proposed and the effects of the LCP matrix on LC ordering are determined numerically. We obtain simple analytical equations for the nematic/isotropic phase diagram boundaries. Our calculation show a nematic-nematic (N/N) first order transition from a guest stabilized to a guest-host stabilized region and the possibility of a reentrant transition from a guest stabilized nematic region to a host only stabilized regime separated by an isotropic phase. A detailed study of thermodynamic variables and interactions on orientational ordering and phases is carried out and the relevance of our predictions to experiments and computer simulations is presented. 相似文献
64.
活性酚醛树脂中羟甲基含量的测定 总被引:12,自引:0,他引:12
本文提出一种酚醛树脂中羟甲基含量的化学分析法,分别以^13CNMR和化学分析法测定酚醛树脂的羟甲基含量。将两种测试结果与已知的投料量进行比较,证明所建立的化学分析法可行。 相似文献
65.
Molecular and nanoscale materials and devices in electronics 总被引:2,自引:0,他引:2
Over the past several years, there have been many significant advances toward the realization of electronic computers integrated on the molecular scale and a much greater understanding of the types of materials that will be useful in molecular devices and their properties. It was demonstrated that individual molecules could serve as incomprehensibly tiny switch and wire one million times smaller than those on conventional silicon microchip. This has resulted very recently in the assembly and demonstration of tiny computer logic circuits built from such molecular scale devices. The purpose of this review is to provide a general introduction to molecular and nanoscale materials and devices in electronics. 相似文献
66.
Equilibrium geometries, interaction energies, and charge transfer for the intermolecular interactions between BrF and HnX (HF, H2O, and NH3) were studied at the MP2/6-311++G(3d,3p) level. The halogen-bonded geometry and hydrogen-bonded geometry are observed in these interactions. The calculated interaction energies show that the halogen-bonded structures are more stable than the corresponding hydrogen-bonded structures. To study the nature of the intermolecular interactions, symmetry-adapted perturbation theory (SAPT) calculations were carried out and the results indicate that the halogen bonding interactions are dominantly inductive energy in nature, while electrostatic energy governs the hydrogen bonding interactions. 相似文献
67.
固相热分解反应最可几机制的判断 总被引:1,自引:0,他引:1
固相热分解反应最可几机制的判断高永煜,邹文樵,冯仰婕(华东理工大学化学系上海200237)关键词热分解,动力学方程,反应机制固相热分解反应机制的判断,是热分析动力学中令人感兴趣的领域。常用的方法是从含机制函数的非等温积分动力学方程出发,分别用Sest... 相似文献
68.
对铝原子簇Al_n(n=1~10,12,13)已报导过的理论预测几何构型进行合理选择, 用量子化学CNDO/2法研究了单分子一氧化碳在这些簇上取不同吸附位形时的吸附作用。结果表明吸附强度随簇尺度的变化呈“幻数”特性: Al_2、Al_6、Al_(12)簇具有特别高的吸附能, 与实验观测结果相符。采用作者建议的推广电子壳模型可合理解释这一尺度效应。对Al_(12)和Al_(13)簇电子结构的分析进一步支持了壳模型的观点。随着簇的增大, 尺度效应逐步减弱并趋向于体相铝的性质。 相似文献
69.
铝酸钠溶液的紫外吸收峰 总被引:4,自引:0,他引:4
分别用量子化学MNDO和DV-X_α方法计算了二聚铝酸离子[Al_2O(OH)_6]~(2-)和Al(OH)_4~-。结果表明前者旋转势垒很低, 只有10.08 kJ·mol~(-1), 最稳定平衡构型为C_s。用X_α过渡态理论计算获得这两个离子紫外吸收峰的理论值分别为266.6 nm和234.4 nm, 与实验值270.0 nm和230.0 nm相当接近。因此可以认为, 紫外吸收峰270.0 nm和230.0 nm分别为[Al_2O(OH)_6]~(2-)和Al(OH)_4~-离子的最高占有轨道电子向最低空轨道跃迁时产生的吸收峰。计算结果支持铝酸钠溶液中存在二聚铝酸离子的观点。 相似文献
70.
Organic photovoltaic (OPV) cells were fabricated via vacuum vapor deposition with {4-[2-(3-di-cyanomethylidene-5,5-dimethylcyclohexenyl)vinyl]phenyl}di(1-naphthyl)amine (DNP-2CN) as the electron donor, and fullerene (C60) as the electron acceptor. A thin film (10 nm) of tris(8-quinolinolato)aluminum (Alq3) was adopted as the buffer layer. A device based on this DNP-2CN exhibited an open circuit voltage (Voc) of 370 mV, a short-circuit current density (Jsc) of 0.61 mAocm 2, and a white-light power conversion efficiency ( η) of 0.09% (AM1.5, 75 mW.cm^- 2). 相似文献