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991.
Modification of Classical SPM for Slightly Rough Surface Scattering with Low Grazing Angle Incidence
GUO Li-Xin WEI Guo-Hui Kim Cheyoung WU Zhen-Sen 《理论物理通讯》2005,44(5):901-907
Based on the impedance/admittance rough boundaries, the reflection coefficients and the scattering cross section with low grazing angle incidence are obtained for both VV and HH polarizations. The error of the classical perturbation method at grazing angle is overcome for the vertical polarization at a rough Neumann boundary of infinite extent. The derivation of the formulae and the numerical results show that the backscattering cross section depends on the grazing angle to the fourth power for both Neumann and Dirichlet boundary conditions with low grazing angle incidence. Our results can reduce to that of the classical small perturbation method by neglecting the Neumann and Dirichlet boundary conditions. 相似文献
992.
研究了退化的级联三能级原子在施加静磁场后的量子相干效应,系统既可出现单光子电磁诱导透明,也可出现双光子电磁诱导透明以及双光子电磁诱导吸收,这取决于两个驱动场的拉比频率和塞曼分裂的相干性。 Quantum coherence effects in degenerate cascade three-level atom subject to magnetic field are investigated. One-photon EIT, two-photon EIT and two-photon EIA are obtained, due to the coherence between the drive Rabi frequency and Zeeman splitting. 相似文献
993.
994.
Iryna Makarchuk Ana Filipa Santos Seica Frédéric Melin Petra Hellwig 《Current Opinion in Electrochemistry》2021
Spectroelectrochemistry, in combination with plasmonic approaches and infrared spectroscopy, has emerged as a powerful tool in the study of membrane protein redox reactions, both for immobilized monolayer samples and those reintroduced into their native environment. Here the use of nanostructured electrodes for surface enhanced spectroelectrochemistry are discussed. 相似文献
995.
Li Ying-le Huang Ji-ying Wang Ming-jun Gong Shu-hong 《International Journal of Infrared and Millimeter Waves》2008,29(10):982-989
This paper studies the electromagnetic reciprocity among spherical targets. The second scattering field for a target is derived
in detail. The complex scattered field and the bistatic RCS are presented respectively. The simulations for the obtaining
result in Ku wave band show that the size of the principal target affects greatly both the forward scatter and the backward
scatter. The influence of the targets around shows definite periodicity. The second scattered field decrease with the increase
of distance between two targets. The more near the forward area the rounding target is, the bigger its affect is. The magnitude
of the second scattered field is about 10–3 comparing with that of the first scattered field. The size of surrounding particles can be considered as a stated scale when
researching the electromagnetic reciprocity. This kind of interaction for three dimensions can be investigated easy by using
the obtained result and coordinate transformation. 相似文献
996.
Based on the effective-mass approximation and variational approach, excitonic optical properties are investigated theoretically in strained wurtzite (WZ) ZnO/Mg x Zn 1-x O cylindrical quantum dots (QDs) for four different Mg compositions: x = 0.08, 0.14, 0.25, and 0.33, with considering a three-dimensional carrier confinement in QDs and a strong built-in electric field effect due to the piezoelectricity and spontaneous polarization. The ground-state exciton binding energy, the interband emission wavelength, and the radiative lifetime as functions of the QD structural parameters (height and radius) are calculated in detail. The computations are performed in the case of finite band offset. Numerical results elucidate that Mg composition has a significant influence on the exciton states and optical properties of ZnO/Mg x Zn 1 x O QDs. The ground-state exciton binding energy increases with increasing Mg composition and the increment tendency is more prominent for small height QDs. As Mg composition increases, the interband emission wavelength has a blue-shift if the dot height L 3.5 nm, but the interband emission wavelength has a red-shift when L 3.5 nm. Furthermore, the radiative lifetime increases rapidly with increasing Mg composition if the dot height L 3 nm and the increment tendency is more prominent for large height QDs. The physical reason has been analyzed in depth. 相似文献
997.
Polymer-derived ceramics have been used as functional nanocomposites with designable structures and tunable properties. In this report, three types of BCN ceramics were fabricated from boron-modified precursors, which were in turn synthesized by the polymerization of decaborane as boron-rich monomer with diamines as linkages. All of these precursors present high ceramic yield and good solubility in N,N-dimethylformamide and dimethyl sulfoxide. The composition and structure of precursors were characterized using elemental analysis, Fourier-transform infrared, gel permeation chromatography, and nuclear magnetic resonance. The structural evolution during the polymer-to-ceramic process and the microstructure of pyrolyzed BCN ceramics were analyzed in detail. The BCN ceramic with 16 wt. % carbon content derived from alkyldiamines exhibited promising X-band absorption properties. When the sample thickness is only 1.8 mm, the minimum reflection loss reaches −40.9 dB at 15.8 GHz with an effective absorption bandwidth of 5.3 GHz. The simple and processable method for BCN ceramics was developed to satisfy the demand of materials with adjustable electromagnetic wave absorption properties. 相似文献
998.
进气道作为飞机强散射源之一,准确评估其雷达散射截面(RCS)特性一直是当今计算电磁学的研究热点.研究了一种加入阻抗边界条件、前后向迭代的迭代物理光学法,提出一种盒体分割法用于处理几何消隐工作.通过软件开发实现任意金属/介质腔体RCS特性评估,并用相关算例校验软件准确性.在此基础上应用该软件对金属/涂敷介质矩形S弯扩压5器进行数值模拟,获得了扩压器在入射波长0.03 m下的RCS变化规律.改进后的迭代物理光学法适用于任意腔体改型和涂敷吸波材料研究,缩短设计周期. 相似文献
999.
1000.
H. Akou 《等离子体物理论文集》2021,61(1):e202000149
The excitation of upper-hybrid wake electrostatic wave by interaction of an extraordinary Gaussian wave propagating perpendicular to the external magnetic field in a cold homogeneous plasma is investigated using magnetohydrodynamics theory. The plasma oscillations can be excited due to the charge separation appeared by the ponderomotive force of the electromagnetic wave whose frequency is considered in the lower pass band. By obtaining the equation governing the plasma wake, the dependency of the wake amplitude on the physical parameters is studied. It is observed that larger wake oscillation takes place when the pulse length is approximately close to 3λp/π and the X-wave frequency is greater than ωp, which means that the phase velocity is less than the speed of light in vacuum (vp < c). 相似文献