Fe2-xYxMo3O12系列材料的相变及负膨胀性研究

本文对Fe2-xYx(MoO4)3(x=0.0,0.2,0.4,0.5,0.6,0.8,1.0,1.2,1.4,1.6,1.8,2.0)系列材料的相变及负膨胀性能进行了研究.通过对Fe2-xYx( MoO4)3系列材料的XRD和拉曼谱的分析发现,当x≤0.4时Fe2-xYxMo3O12在常温下是单斜结构;当x≥0.5时...     

Efficiency of terahertz detection in electro-optic polymer sensors with interdigitated coplanar electrodes

We discuss the efficiency of an electro-optic （EO） polymer sensor with interdigitated coplanar electrodes. The developed EO sensor is used to detect terahertz radiation via EO sampling. Results show that the sensor improves more significantly detection sensitivity than does a sensor with sandwich configurations.     

Theoretical analysis of optical force density distribution inside subwavelength-diameter optical fibers

We investigate the microscopic optical force density distributions respectively inside a subwavelength-diameter(SD)fiber with flat endface and inside one with oblique endface by using a finite-difference time-domain(FDTD) method.Optical force density distributions at the fiber endfaces can now be readily available. The complete knowledge of optical force density distributions not only reveal features regarding the microscopic near-field optomechanical interaction, but also provide straightforward explanations for the sideway deflections and other mechanical motions. Our results can provide a useful reference for better understanding the mechanical influence when light transports in a microscale or nanoscale structure and for developing future highly-sensitive optomechanical devices.     

各向异性对半圆形河谷散射影响的数值分析

半圆形河谷场地可构造为包含河谷的广义子结构和具有规则边界的开挖场地两部分，基于土-结构相互作用SSI原理，建立子结构控制方程。利用比例边界有限元SBFEM求解开挖场地动刚度，解析求解各向异性介质自由场qP波波动，将两者代入控制方程，可求得广义结构的动力响应。与文献中各向同性半空间中半圆形河谷在P波入射下的位移结果对比，验证了方法的精度和有效性。进一步分析了椭圆各向异性和非椭圆各向异性对半圆形河谷在qP波入射下位移分布的影响。数值算例显示，介质的各向异性改变了半圆形河谷散射位移的空间分布，增大了水平向位移的峰值；同时，介质的各向异性加剧了入射角对散射波场位移分布的影响。     

表面等离激元增强的光和物质相互作用

表面等离激元近年来受到了广泛的关注.得益于表面等离激元的强局域约束作用,光场和能量被限制在亚波长尺度上,因而各种光和物质相互作用可得到显著的增强.表面等离激元的特性与材料、形貌、结构密切相关,相应的共振波长可覆盖紫外、可见光、近红外到远红外的光谱波段.由于表面等离激元的强局域电场,光与物质的相互作用,如荧光、拉曼散射、非线性光学、光热转换、光-声效应、催化、光伏转换等,都得以显著增强.本文简要回顾了表面等离激元的物理特性,具体讨论了各种基于表面等离激元增强的光和物质相互作用机理及相关应用,并探讨了存在的问题和进一步发展的方向.本文旨在为构造更高性能的表面等离激元器件,发展相关技术,进一步拓展表面等离激元的应用领域提供有益的参考.     

Interface coupling effects of weakly nonlinear Rayleigh–Taylor instability with double interfaces

Taking the Rayleigh–Taylor instability with double interfaces as the research object,the interface coupling effects in the weakly nonlinear regime are studied numerically.The variation of Atwood numbers on the two interfaces and the variation of the thickness between them are taken into consideration.It is shown that,when the Atwood number on the lower interface is small,the amplitude of perturbation growth on the lower interface is positively related with the Atwood number on the upper interface.However,it is negatively related when the Atwood number on the lower interface is large.The above phenomenon is quantitatively studied using an analytical formula and the underlying physical mechanism is presented.     

β-硝基-5,10,15,20-四(2-甲氧基苯基)卟啉合成及其阻旋异构

在采用区域选择性硝化方法合成β-硝基-5,10,15,20-四芳基卟啉铜、镍配合物的过程中,发现并通过核磁等方法分析了5,10,15,20-四(2-甲氧基苯基)卟啉及其相应β-硝基取代物的阻旋异构现象.图谱分析表明,与其结构类似的5,10,15,20-四(2-羟基苯基)卟啉及5,10,15,20-四(4-甲氧基苯基)卟啉系列化合物没有该阻旋异构现象,说明邻位甲氧基阻碍了苯环与芳环之间C-C单键的旋转.进一步通过Chemdraw 3D Ultra软件能量最小化计算,讨论了阻转异构体可能的方式.     

Experimental studies of extraordinary light transmission through periodic arrays of subwavelength square and rectangular holes in metal films

We fabricate a series of periodic arrays of subwavelength square and rectangular air holes on gold films, and measure the transmission spectra of these metallic nanostructures. By changing some geometrical and physical parameters, such as array period, air hole size and shape, and the incident light polarization, we verify that both global surface plasmon resonance and localized waveguide mode resonance are influential on enhancing the transmission of light through nanostructured metal films. These two resonances induce different behaviours of transmission peak shift. The transmission through the rectangular air-hole structures exhibits an obvious polarization effect dependent on the morphology. Numerical simulations are also made by a plane-wave transfer-matrix method and in good consistency with the experimental results.     

Superconducting phase qubits with shadow-evaporated Josephson junctions

We develop a fabrication process for the superconducting phase qubits in which Josephson junctions for both the qubit and superconducting quantum interference device(SQUID) detector are prepared by shadow evaporation with a suspended bridge. Al junctions with areas as small as 0.05 μm~2 are fabricated for the qubit, in which the number of the decoherencecausing two-level systems(TLS) residing in the tunnel barrier and proportional to the junction area are greatly reduced. The measured energy spectrum shows no avoided crossing arising from coherent TLS in the experimentally reachable flux bias range of the phase qubit, which demonstrates the energy relaxation time T_1 and dephasing time T_φ on the order of 100 ns and 50 ns, respectively. We discuss several possible origins of decoherence from incoherent or weakly-coupled coherent TLS and further improvements of the qubit performance.     

新型β-取代阳离子卟啉光敏剂合成及其与DNA相互作用

在5,10,15,20-四苯基卟啉及其金属配合物的β位引入阳离子型修饰基团溴化吡啶鎓盐, 得到β-[2-(6-吡啶溴化盐)己氧基]萘基-5,10,15,20-四苯基卟啉及其Cu(II), Ni(II), Zn(II)配合物. 通过IR, UV, ¹H NMR, MS以及元素分析对新化合物进行了结构表征. 作为光动力治疗光敏剂与pBR322质粒DNA的相互作用研究表明, 它们对DNA具有良好的光敏切割效果和结合能力, 通过与小牛胸腺DNA相互作用初步研究了它们与DNA的作用模式.