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We investigate theoretically the electron transport properties of a two-sublevel quantum wire irradiated by a strong laser field resonant with the quasiparticle transition at low temperatures. Using the method of the Keldysh equation of motion for nonequilibrium Green function, we examine the time-averaged conductance for the system with photon polarization parallel and perpendicular to the tunnelling current direction, respectively. We demonstrate that, by analysing some numerical examples, a feature of absolute negative conductance appears in the parallel case, while the conductance shows a symmetry distributed peaks in the Derpendicular case. 相似文献
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漆树漆酶的催化氧化作用(ⅫⅡ) 总被引:2,自引:0,他引:2
以5,6-二溴-2,3-二氰基氢醌为底物,在PH4.50条件下,用分光光度法考察了FeSO4对漆树漆酶催化氧化反应的影响。结表明,在本文实验条件下SO4^2-离子对酶促反应的影响基本可以忽略,而Fe^2离子对漆酶的催化氧化反应则有明显的竞争性抑制作用,研究证实,Fe^2+离子的抑制作用是通过它还原酶促反应的产物半醌自由基阴离子来实现的。 相似文献
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机械补偿法变焦镜头三个发展阶段的概况和发展方向 总被引:2,自引:0,他引:2
叙述机械补偿法变焦镜头三个不同的发展阶段、特点和发展方向。 相似文献
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Fluorescence Enhancement of a Polymer Planar Waveguide Doped with Rhodamine B and Ag Nanoparticles
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Planar polymer multi-model waveguides doped with Ag nano-particles and rhodamine B are fabricated and investigated by the spectroscopy analysis method as well as the M-line method. Experimental results shown that fluorescence enhancement occurs when excited by a wide band wavelength with Ag nano-particle concentration at a certain level. The maximum enhancement factor in our experiment is obtained to be about 3.8 when excited by 350 nm. Our study may have potential applications in polymers optical elements, such as polymer waveguide lasers and amplifiers. 相似文献
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We theoretically study the low temperature electron transport properties of a weak Rashba spin-orbit coupling (SOC) semiconductor quantum wire connected nonadiabatically to two electrode leads without SOC. The wire and the leads are defined by a parabolic confining potential, and the influence of both the wire-lead connection and the Rashba SOC on the electron transport is treated analytically by means of scattering matrix within effective free-electron approximation. From analytical analysis and numerical examples, we find that the system shows some fractional quantum conductance behaviour, and for some particular wire width a pure spin polarized current exists. Our result may imply a simple method for the design of a spin filter without involving any magnetic materials or magnetic fields. 相似文献
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Electron Transport of an Impurity Quantum Wire Under THz Electromagnetic Field Illumination
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We theoretically investigate the effect of a single finite-size attractive impurity on the electron transport of a semiconductor quantum wire under the influence of a terahertz electromagnetic field illumination. In the freeparticle framework, the time-dependent electronic states are obtained by introducing an unitary transformation,and the electronic transmission of the system is obtained by using the scattering matrix approach. In the case of the field frequency resonant with the lateral energy spacing of the two lowest levels, a step-like structure for the transmission probability versus the total electron energy is predicted. Furthermore, due to the interplay between the single impurity and the applied field, the transmission probability curve in the non-resonant case shows a structure of a resonance dip on the interference pattern background with certain parameters of the impurity. 相似文献
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由中国核物理学会委托南京大学筹备召开的全国穆斯堡尔谱学会议于1981年6月16日至21日在南京召开.83个单位的136位代表参加了会议. 穆斯堡尔谱学是利用原于核对γ射线的无反冲共振吸收研究物质微观结构的新学科,它在自然科学的各个领域都有广泛的应用. 会议期间,代表就穆斯堡尔 相似文献