共振光散射法测定环境水样中痕量锡

基于在Tris-HCl介质中,痕量锡对氯酚红-人血白蛋白-十二烷基硫酸钠体系的共振散射光谱有明显的猝灭作用;考察了它们的光谱特征、影响因素和适宜的反应条件;确定了散射光强度与Sn2 的关系,从而建立了测定痕量锡的共振光散射新方法.该法在室温下进行,操作方便,灵敏度高和选择性好.其线性范围为0.2-4.0μg/L,检出限0.12μg/L,用于环境水样中痕量Sn2 的测定,相对标准偏差小于3.1%,加标回收率为95.5%-100.5%,效果良好.     

2-(2-喹啉偶氮)-5-二甲氨基苯胺光度法测定铜

在pH=4.0的磷酸盐缓冲介质中,CTMAB存在下,2-(2-喹啉偶氮)-5-二甲氨基苯胺(QADMAA)与铜反应生成2:1稳定络合物,络合物λmax=580nm,ε=1.14×105L·mol-1·cm-1.铜含量在0.01-0.6μg/mL内符合比耳定律,方法用于环境样品中铜的测定,结果令人满意.     

具Hardy-Sobolev临界指数的奇异椭圆方程多解的存在性

运用变分方法研究了下面问题-Δpu=μupx(s)s-2u f(x,u),x∈Ω,u=0,x∈Ω,多重解的存在性,其中Ω是一个具有光滑边界的有界区域.     

The AB2-XA1 electronic transition of NO2: A rovibronic survey covering 14 300-18 000 cm

More than 250 rotationally resolved vibrational bands of the A²B₂-X²A₁ electronic transition of ¹⁵NO₂ have been observed in the 14 300-18 000 cm⁻¹ range. The bands have been recorded in a recently constructed setup designed for high resolution spectroscopy of jet cooled molecules by combining time gated fluorescence spectroscopy and molecular beam techniques. The majority of the observed bands has been rotationally assigned and can be identified as transitions starting from the vibrational ground state or from vibrationally excited (hot band) states. An exceptionally strong band is located at 14 851 cm⁻¹ and studied in more detail as a typical benchmark transition to monitor ¹⁵NO₂ in atmospheric remote sensing experiments. Standard rotational fit routines provide band origins, rotational and spin rotation constants. A subset of 177 vibronic levels of ²B₂ vibronic symmetry has been analyzed in the energy range between 14 300 and 17 250 cm⁻¹, in terms of integrated density and using Next Neighbor Distribution. It is found that the overall statistical properties and polyad structure of ¹⁵NO₂ are comparable to those of ¹⁴NO₂ but that the internal structures of the polyads are completely different. This is a direct consequence of the X²A₁-A²B₂ vibronic mixing.     

Solid-phase epitaxy of CaSi2 on Si(1 1 1) and the Schottky-barrier height of CaSi2/Si(1 1 1)

Thin Ca films were evaporated on Si(1 1 1) under UHV conditions and subsequently annealed in the temperature range 200–650 °C. The interdiffusion of Ca and Si was examined by ex situ Auger depth profiling. In situ monitoring of the Si 2p core-level shift by X-ray photoemission spectroscopy (XPS) was employed to study the silicide formation process. The formation temperature of CaSi₂ films on Si(1 1 1) was found to be about 350 °C. Epitaxial growth takes place at T≥400 °C. The morphology of the films, measured by atomic force microscopy (AFM), was correlated with their crystallinity as analyzed by X-ray diffraction (XRD). According to measurements of temperature-dependent I–V characteristics and internal photoemission the Schottky-barrier height of CaSi₂ on Si(1 1 1) amounts to qΦ_Bn=0.25 eV on n-type and to qΦ_Bp=0.82 eV on p-type silicon.     

HgCl2/I2复合催化剂协同催化合成异丙醇钇的研究

以金属钇和异丙醇为原料，以HgCl2/I2为复合催化剂，通过对金属钇的机械加工以增加其比表面，并将异丙醇脱水使其含水量降低至0．05％，体系在82℃回流5h，经过滤、减压蒸馏，得到了白色海绵状异丙醇钇，其产率高达83％，合成时间比文献报道的缩短了19h，产率提高了8％。文章确定了催化剂的最佳用量为20gY加入60mg HgCl2/I2，研究了合成产率与HgCl2/I2催化剂和HgCl2催化剂的依赖关系及异丙醇中含水量对合成产率的影响，并对HgCl2/I2的催化作用机理进行了初步探讨。     

用Java实现网上结构图实验仿真

基于线性系统仿真的连接矩阵方法，用Java语言开发面向结构图的实验仿真程序，以Applet小应用程序的形式插入网页中运行，实现了信号与系统网上实验教学中的结构图实验仿真。经试用，程序在浏览器中运行正常，可以完成一般线性系统仿真，与以MATLAB，LABView等程序开发的实验仿真程序相比，该程序运行环境简单，几乎所有常用的Web浏览器都支持Java运行，不需另行安装相应组件。对于线性系统结构图，实现了所见即所得的图形化编程环境，具有较好的人机交互性。     

一类广义Schrdinger算子的自伴性与本质谱

本文在一类 Ｌｐ位势Ｖ（ｘ）下建立了广义Ｓｃｈｒｏｄｉｎｇｅｒ算子Ｈ＝（－Δ）ｍ＋Ｖ（ｘ）在Ｃ∞０（Ｒｎ）上的本质自伴性，给出了Ｈ的本质谱的分布．     

Coxeter Transformation and Quasiquivers

Mathematical Notes -     

非对称量子阱中非线性光学吸收系数的计算

非对称量子阱中的非线性光学效应因其潜在的实用价值而引起人们的广泛关注,而量子阱内带间的光学吸收问题对研究远红外光学探测器件具有重要的理论指导意义.以Pschl-Teller势阱为例研究了影响非对称量子阱中的非线性光学吸收系数的因素.考虑到带间的电子弛豫,用量子力学中的密度矩阵算符理论导出了Pschl-Teller势阱中的线性与三阶非线性光学吸收系数的表达式.因该势阱中有两个可调参数,通过调节系统的参数,发现该系统的非线性光学吸收系数呈规律性的变化.以典型的GaAs/AlGaAs非对称量子阱为例作了数值计算,通过调节系统的参数,数值计算结果表明,入射光强以及系统的非对称性对量子阱的非线性光学吸收系数有较大的影响,从而为实验上研究非对称量子阱的非线性光学效应提供了必要的理论依据.