A Comparative Study on the Influence of Submonolayer Coverage Sn on SERS of Au and Pt Substrates

Since the discovery of the surface enhanced Raman scattering (SERS) in mid-1970's,great efforts have been devoted to understand the enhancement mechanism as well as to extend the SERS system and application. There has been a consensus that the electromagnetic enhancement (EM) and chemical enhancement are the two important SERS mechanisms but each of them can only explain some of experimental results^[1,2] The EM mechanism relies on the surface plasmon resonance under a proper incident laser excitation. Strong EM enhancement has been observed on metals such as Cu, Ag and Au but not on transition metals such as Pt. However, the surface electronic properties can be modulated through submonolayer quantity modification of foreign metal atoms, hi this paper, we report a comparative study on SERS of Au and Pt in the presence of underpotentially deposited (UPD) submonolayer Sn.     

测量土体内部位移场的一种新方法

采用数字图像相关分析方法,对砂土受均布荷载作用的全场位移进行了测试分析,并与传统的布辛奈斯克解计算结果相比较,得到了满意的效果,该法在连续体的位移场测量方面已有广泛应用,而用于土体的位移测量却少见,测得位移场后,再根据土的本构关系即可求得相应的应力场。这为土体模型试验中量测变形开拓了新的途径,也为岩土和地基工程的深入研究提供了一种更有效的方法。     

Judd-Ofelt Analysis on Trifluoroacetate Europium Complexes for Liquid Laser Media

Four europium trifluoroacetate complexes, Eu(CF₃COO)₃·bpy(bpy=2,2′-bipyridine)(1), Eu(CF₃COO)₃· phen(phen=1,10-phenanthroline)(2), Eu(CF₃COO)₃·2bp(bp=benzophenone)(3) and Eu(CF₃COO)₃·2tppo(tppo=triphenyl-phosphine oxide)(4) were synthesized and characterized by elemental analysis, Fourier transform infrared(FTIR) spectroscopy, photoluminescence(PL) spectroscopy and thermogravimetric analysis(TGA). The PL spectra of the complexes at room temperature show the strong typical Eu³⁺ ion red emission, due to the efficient energy “antenna absorption” of ligands and transitions of Eu³⁺ ion between ⁵D₀→⁷F_J(J=0―4). The long lifetime and high quantum yield reflect that the multiphonon relaxations by coupling to O―H and C―H vibrations were reduced. According to the photoluminescent spectra, the Judd-Ofelt parameters Ω₂ and Ω₄ of the complexes were calculated and the radiative properties were also presented. The ⁵D₀ radiative lifetime, quantum yield and the stimulated emission cross-section of the complexes are excellent, which prove that they have promising optical properties for liquid laser. The thermal analyses indicate that they are quite stable to heat.     

关于加加速度的若干机械运动分析及MATLAB模拟

分析了和加加速度有关的若干机械运动的运动特点,并用MATLAB作了计算机模拟。     

Ag110m的衰变纲图

利用γ闪烁谱仪和γ—γ符合谱仪,我们对Ag^110m衰变的γ射线进行了研究;提出了一个修正的衰变纲图,认为Cd¹¹⁰有656kev,1473kev,1540kev,2160kev,2219kev,2476kev和2924kev七个激发能级,包含有能量为448,620,656,679,705,741,764,817,884,936,1384,1473,1504和1560kev的14条γ射线。用符合方法,我们除了证实一般公认为有级联关系的γ射线之间有符合之外,还确定了1560kevγ射线在衰变图中的位置,证实了764kevγ射线应该放在1504kevγ射线的前面,并且指出,817kevγ射线是属于1473kev能级到656kev能级间的跃迁的。此外,还观察到1820kev和2268kev两个峰;经过用吸收方法分析,指出它们是由于低能量的γ射线“堆积”起来的迭加峰。     

Mn:KNSBN晶体中背向光散射与光学二极管效应

用单束毫瓦级的632.8nmHe-Ne激光入射到掺Mn的KNSBN晶体中,观察到强烈的背向散射,同时观察到一种与背向散射相联系的光学二极管效应。在一定范围内,光学二极管的时间响应常数τ与晶体表面的入射光强成反比,以K₉玻璃片作反馈镜,可将τ降低一个数量级。已取得τ=1.5s及大于15.3的正、反向透过率比。对实验结果给出理论解释。 关键词：     

Mn：KNSBN晶体中弱入射光高反射率四波混频相位共轭

功率为1mW左右的He-Ne激光束在Mn:KNSBN晶体中实现四波混频相位共轭。入射光相对于晶体主光轴的取向及入射光偏振组态对相位共轭反射率都有很大的影响。当物光近于布儒斯特角入射时,反射率可达60％。建立时间约为60sec的光折变光栅具有18hr左右的寿命。晶体中观察到诱导四波混频相位共轭。     

非线性传输线中的孤子

分析了波在非线性无色散传输线和非线性有色散传输线中的传播情况,从而引入孤子的概念,分析了孤子的性质,并介绍了有关的实验.     

热自聚焦诱导光折变非对称自散焦

用波长为５３２ｎｍ的高斯光束入射到掺杂的ＫＮＳＢＮ晶体中，对足够大的光强，观察到由热自聚焦效应诱导产生的光折变非对称自散焦．非对称自散焦的空间分布与性质都有别于噪声受激放大．它对自泵浦相位共轭无甚贡献．对开始产生非对称自散焦时晶体中光束的直径作出估计 关键词：     

Fluorescence Detection and Buffer Gas Cooling of Trapped Mercury Ions in Paul Trap

Pig ions are confined in a hyperboloid ion trap. With the rf discharge ^202 Hg isotope lamp, the fluorescence signal of trapped Hg ions is observed. By means of buffer gas cooling, the ionic temperature is reduced. As a result, the trapping time is increased and the signal-to-noise ratio （SNR） of the fluorescent signal is improved. The temperature of ion cloud is estimated by measuring the space charge shift.