Hyperfine structure and absolute frequency measurements of <Superscript>127</Superscript><Emphasis Type="Italic">I</Emphasis><Subscript>2</Subscript> transitions with monolithic Nd:YAG 561-nm lasers

The precision hyperfine structures of the ¹²⁷ I ₂ transitions at 561.4 nm are measured by the heterodyne beat between two home-made ¹²⁷ I ₂-stabilized Nd:YAG lasers. The theoretical distributions of the observed transitions’ hyperfine sublevels are used to identify the two transitions. High-accuracy hyperfine constants are obtained by fitting the measured hyperfine splittings to the four-term Hamiltonian, which includes the electric quadruple, spin-rotation, tensor spin–spin and scalar spin–spin interactions. The absolute frequencies of the observed four transitions are measured by an optical frequency comb based on a mode-locked erbium-fiber laser.     

飞秒化学的先驱者--记诺贝尔化学奖得主Ahmed H.Zewail教授

1999年10月12日,瑞典皇家科学院将今年的诺贝尔化学奖授予埃及和美国双重国籍的物理化学和化学物理学家Ahmed H.Zewail,以表彰他在利用飞秒激光脉冲研究化学反应方面的开拓性工作.各国科学家都认为这是一个众望所归的结果.在最近几年里,Zewail教授一直是诺贝尔化学奖呼声很高的候选人,并得到多次提名.     

Photoassisted degradation of dye pollutants in aqueous TiO2 dispersions under irradiation by visible light

The photoassisted degradation of two dye compounds, erythrosine and rhodamine B, has been investigated in an aqueous TiO₂ dispersion under irradiation by visible light. The compounds can be easily decomposed photochemically by visible light, which provides possibly a new approach for the treatment of dye pollutants in wastewater.     

Tailoring Zinc Oxide Nanowires for High Performance Amperometric Glucose Sensor

ZnO nanowire was tailored both physically and chemically to immobilize the enzyme glucose oxidase (GOD) for construction of a glucose sensor with high performance, which was ascribed to its high specific surface area and high isoelectric point value for efficient immobilization of high concentration of acidic enzymes and the mediating effect by the redox reaction of ZnO nanowires. The apparent Michaelis constants J_max, and K_M were adjusted in a large scope by tailoring the thickness of the GOD/ZnO nanowire layer and the enzyme load in the nanowired network. Thus, a variety of linear region, sensitivities and reaction rates of the sensor could be easily achieved. Moreover, the glucose sensor showed long term stability with the incorporation of the inorganic zinc oxide nanowire.     

单标准FIA梯度校正催化动力学的光度测定法

催化动力学光度测定法有较高的灵敏度和选择性,但对实验条件要求苛刻,操作复杂,再现性较差。流动注射分析法(FIA)的引入简化了催化动力学测定的操作步骤,提高了再现性,然而连续FIA方法仅适用于催化反应较快的体系,本文将微机与FIA在线联机,利用FIA停流技术提高测试灵敏度,由FIA梯度校正原理用单标准溶液制备“标准系列,建     

46.7MeV/u 12C诱发核反应中的双质子干涉研究

本文讨论了46.7MeV/u ¹²C+⁵⁸Ni,¹¹⁵In,¹⁹⁷An实验中双质子干涉的研究结果,研究了零寿命Koonin模型中核力、库仑力及费米统计对关联函数的影响,并从实验中提取了发射源的半径参数r₀,实验发现r₀随着靶核质量的增加而增加,实验中还研究了发射源的大小与两个关联粒子能量和E₁+M₂的关系,得出的r₀值随着E₁+E₂的增加而减少,反映了高能质子主要来源于反应的早期.     

双脉冲驱动锗薄膜靶高增益X射线激光实验

利用窄脉宽,低能量并具有一定时间间隔的两束激光脉冲驱动薄膜锗靶,获得高增益X射线激光的实验方法和结果,每束入射激光能量仅几十焦耳,脉宽100—160ps,两脉冲时间间隔35Ops,所用的靶为锗薄膜靶,其长为10mm,厚为34.0nm,实验中利用掠人射光栅谱仪观测到类氖锗3s—3PJ=0—1和J=2—1两条激光线,它们的波长分别为19.61nm和23.63nm,折射角均为12mrad,人发散用分别小于10.8mrad和17.8mrad. 关键词：     

Synthesis and structure of a µ‐oxo diiron(III) complex with an N‐pyridylmethyl‐N,N‐bis(4‐methylbenzimidazol‐2‐yl)amine ligand and its catalytic property for hydrocarbon oxidation

A µ‐oxo diiron(III) complex [{Fe(pbba)Cl}₂(µ‐O)]Cl₂ (1, pbba = N‐pyridylmethyl‐N,N‐bis(4‐methylbenzimidazol‐2‐yl)amine) bearing multi‐imidazolyl motifs was synthesized and characterized by X‐ray crystallography to closely mimic the structural features of methane monooxygenase. As shown by its X‐ray crystal structure, complex 1 is a centrosymmetric dimer with an Fe? O? Fe angle of 180° , and pseudo‐octahedral around each iron(III) center. The catalytic ability of title compound in the oxidation of alkane and alkene is investigated by employing tert‐butylhydroperoxide and m‐chloroperbenzoic acid as oxidants under mild conditions. The catalytic oxidation results showed that radical intermediate dominates the oxidation process. Copyright © 2008 John Wiley & Sons, Ltd.     

过零时间法的实验模拟与理论分析

介绍了过零时间法的原理及在重离子核反应中的应用,通过精密脉冲发生器对过零时间法进行了模拟检验,并用Laplace变换方法对过零时间法进行了理论分析计算,模拟和分析都取得了满意的结果.