环戊烷分子的电子动量谱

报导了在高分辨率电子动量谱仪上获得的环戊烷分子的结合能谱和动量谱的实验结果,并用Hartree-Fock方法和密度泛函方法做了理论计算.实验得到的环戊烷分子各电子轨道的电离能值与光电子谱得到的数据一致,动量分布的实验结果也与理论计算基本吻合.     

Analysis of the resistive switching behaviors of vanadium oxide thin film

We demonstrate the polarization of resistive switching for a Cu/VOx/Cu memory cell.The switching behaviors of Cu/VOx/Cu cell are tested by using a semiconductor device analyzer(Agilent B1500A),and the relative micro-analysis of I-V characteristics of VOx/Cu is characterized by using a conductive atomic force microscope(CAFM).The I-V test results indicate that both the forming and the reversible resistive switching between low resistance state(LRS) and high resistance state(HRS) can be observed under either positive or negative sweep.The CAFM images for LRS and HRS directly exhibit evidence for the formation and rupture of filaments based on positive or negative voltage.The Cu/VOx/Cu sandwiched structure exhibits reversible resistive switching behavior and shows potential applications in the next generation of nonvolatile memory.     

Recent advancements in analytical methods of phosphodiesterase 5 inhibitors and their metabolitesEI北大核心CSCD

磷酸二酯酶5抑制剂(PDE5i)用于治疗勃起功能障碍和肺动脉高压等疾病。因PDE5i类药物种类繁多,理化性质各异,在体内代谢迅速且具有多种代谢途径,故生物样本检验难度大。本文介绍了PDE5i类药物及其代谢物,总结了生物样本中该类物质的沉淀蛋白法、液-液萃取法、固相萃取法和固相微萃取法等前处理方法,综述了高效液相色谱法、液相色谱质谱联用法、荧光光谱法和电化学分析法等检测方法,展望了PDE5i及其代谢物分析的未来发展方向,以期为PDE5i的药物监测和法庭科学毒物检验提供参考。     

高功率激光装置光束精密调控性能研究进展

光束精密调控是惯性约束聚变(ICF)研究对激光驱动器的基本需求,它是一项装置层面的系统工程。主要介绍了中国工程物理研究院激光聚变研究中心近年来在靶面光强控制、脉冲波形控制、光束近场控制以及在新型光束探索方面所取得的重要进展。     

Non-collinear phase-matching sum-frequency generation based on boundary total reflection in bulk KDP

Collinear phase-matching of sum-frequency generation(SFG) has been studied thoroughly previously, while non-collinear schemes are sometimes more flexible in application. However, this phase-matching type is more difficult to meet and control. We employ a convenient method to obtain harmonic generation in bulk potassium dihydrogen phosphate(KDP), using an incident wave vector and a reflected wave vector to create a triangle phase-matching relationship. With a simple, flexible set-up, we can observe 351 nm SFG, and the conversion efficiency is up to ~3.6% per reflection. Furthermore, we believe this approach has potential application value and improvement space.     

Characterization of a nano line width reference material based on metrological scanning electron microscope

The line width (often synonymously used for critical dimension, CD) is a crucial parameter in integrated circuits. To accurately control CD values in manufacturing, a reasonable CD reference material is required to calibrate the corresponding instruments. We develop a new reference material with nominal CDs of 160 nm, 80 nm, and 40 nm. The line features are investigated based on the metrological scanning electron microscope which is developed by the National Institute of Metrology (NIM) in China. Also, we propose a new characterization method for the precise measurement of CD values. After filtering and leveling the intensity profiles, the line features are characterized by the combination model of the Gaussian and Lorentz functions. The left and right edges of CD are automatically extracted with the profile decomposition and k-means algorithm. Then the width of the two edges at the half intensity position is regarded as the standard CD value. Finally, the measurement results are evaluated in terms of the sample, instrument, algorithm, and repeatability. The experiments indicate efficiency of the proposed method which can be easily applied in practice to accurately characterize CDs.     

含双哌啶基手性β-氨基醇的合成及其在二乙基锌与芳香醛加成中的手性诱导作用

合成了五个含双哌啶基的手性β-氨基醇化合物(2a,2b,4b~4d),其结构经1H NMR,13C NMR,IR和MS表征,其中4b~4d未见文献报道。2和4在二乙基锌对芳香醛的不对称加成反应中均显示出优良的手性诱导作用,以苯甲醛为底物时,所得仲醇的ee值最高达93.1%。     

Poisson线瞄准技术初步研究

Poisson斑的中心可以在很长的距离内保持与轴心共线因而能实现高精度的对心瞄准,这一技术被称为Poisson线技术.利用数值模拟和实验验证对Poisson线瞄准技术进行了初步研究.通过数值模拟发现,Poisson线上的光强随着离圆屏距离的增加而增大;Poisson斑直径随着圆屏直径增加而减小、随着距离增加而增加;其方向平行于入射激光束并过圆屏中心（待瞄准点）.Poisson线对圆屏的倾斜非常不敏感,但是对中心的偏移非常敏感.模拟中发现Poisson线对10 μm的中心偏移敏感,初步实验验证Poisson线可实现50 μm的对心误差调节.     

Anomalous thermal expansion and spontaneous magnetostriction of Gd2Fe16Cr compound

The structural and the magnetic properties of Gd 2 Fe 16 Cr compound are investigated by x-ray diffraction and magnetization measurements.The Gd 2 Fe 16 Cr compound has a rhombohedral Th 2 Zn 17-type structure.There exist an anisotropic strong spontaneous magnetostriction and a negative thermal expansion in the magnetic state of Gd 2 Fe 16 Cr compound.The average thermal expansion coefficient ā=-7.03 × 10-6 /K in a temperature range of 294-454 K and ā=-1.31 × 10-5 /K in 454-572 K are obtained.The spontaneous magnetostrictive deformation and the Curie temperature are discussed.     

Ultraviolet laser-induced photovoltaic effects in miscut ferroelectric LiNbO3 single crystals

This paper investigates the photovoltaic properties of miscut LiNbO 3 single crystal with different thicknesses under irradiation of a 248 nm ultraviolet laser pulse with 20 ns duration without an applied bias.Nanosecond photovoltaic response is observed and faster rise time is obtained in thinner samples.In accord with the 248 nm laser duration,the full width at half maximum of the photovoltaic signals keeps a constant of ～ 20 ns.With decrease of the crystal thickness,the photovoltaic sensitivity was improved rapidly at first and then decreased,and the maximum photovoltage occurred at 0.38 mm-thick single crystal.The present results demonstrate that decreasing the LiNbO3 single crystal thickness can obtain faster response time and improve the photovoltaic sensitivity.