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72.
Conventional approaches to control and shape the scattering pattems of light generated by different nanostructures are mostly based on engineering of their electric response due to the fact that most metallic nanostructures support only electric resonances in the optical frequency range. Recently, fuelled by the fast development in the fields of metamaterials and plasmonics, artificial optically-induced magnetic responses have been demonstrated for various nanostructures. This kind of response can be employed to provide an extra degree of freedom for the efficient control and shaping of the scattering patterns of nanoparticles and nanoantennas. Here we review the recent progress in this research direction of nanoparticle scattering shaping and control through the interference of both electric and optically-induced magnetic responses. We discuss the magnetic resonances supported by various structures in different spectral regimes, and then summarize the original results on the scattering shaping involving both electric and magnetic responses, based on the interference of both spectrally separated (with different resonant wavelengths) and overlapped dipoles (with the same resonant wavelength), and also other higher-order modes. Finally, we discuss the scattering control utilizing Fano resonances associated with the magnetic responses. 相似文献
73.
Large coercivity and unconventional exchange coupling in manganese-oxide-coated manganese gallium nanoparticles 下载免费PDF全文
The microstructures and magnetic properties of nanoparticles, each composed of an antiferromagnetic (AFM) manganese-oxide shell and a ferromagnetic-like core of manganese-gallium (MnGa) compounds, are studied. The coreshell structure is confirmed by transmission electron microscope (TEM). The ferromagnetic-like core contains three kinds of MnGa binary compounds, i.e., ferrimagnetic (FI) DO22-type MnaGa, ferromagnetic (FM) Mn8Gas, and AFM DO19-type Mn3Ga, of which the first two correspond respectively to a hard magnetic phase and to a soft one. Decoupling effect between these two phases is found at low temperature, which weakens gradually with increasing temperature and disappears above 200 K. The exchange bias (EB) effect is observed simultaneously, which is caused by the exchange coupling between the AFM shell and FM-like core. A large coercivity of 6.96 kOe (1Oe = 79.5775 A·m^-1) and a maximum EB value of 0.45 kOe are achieved at 300 K and 200 K respectively. 相似文献
74.
Segregation of alloying atoms at a tilt symmetric grain boundary in tungsten and their strengthening and embrittling effects 下载免费PDF全文
We investigate the segregation behavior of alloying atoms (Sr, Th, In, Cd, Ag, Sc, Au, Zn, Cu, Mn, Cr, and Ti) near Z3 ( 111 ) [1]-0] tilt symmetric grain boundary (GB) in tungsten and their effects on the intergranular embrittlement by performing first-principles calculations. The calculated segregation energies suggest that Ag, Au, Cd, In, Sc, Sr, Th, and Ti prefer to occupy the site in the mirror plane of the GB, while Cu, Cr, Mn, and Zn intend to locate at the first layer nearby the GB core. The calculated strengthening energies predict Sr, Th, In, Cd, Ag, Sc, Au, Ti, and Zn act as embrittlers while Cu, Cr, and Mn act as cohesion enhancers. The correlation of the alloying atom's metal radius with strengthening energy is strong enough to predict the strengthening and embrittling behavior of alloying atoms; that is, the alloying atom with larger metal radius than W acts as an embrittler and the one with smaller metal radius acts as a cohesion enhancer. 相似文献
75.
Analysis of detection limit to time-resolved coherent anti-Stokes Raman scattering nanoscopy 下载免费PDF全文
In the implementation of CARS nanoscopy, signal strength decreases with focal volume size decreasing. A crucial problem that remains to be solved is whether the reduced signal generated in the suppressed focal volume can be detected. Here reported is a theoretical analysis of detection limit (DL) to time-resolved CARS (T-CARS) nanoscopy based on our proposed additional probe-beam-induced phonon depletion (APIPD) method for the low concentration samples. In order to acquire a detailed shot-noise limited signal-to-noise (SNR) and the involved parameters to evaluate DL, the T-CARS process is described with full quantum theory to estimate the extreme power density levels of the pump and Stokes beams determined by saturation behavior of coherent phonons, which are both actually on the order of ~ 109 W/cm2. When the pump and Stokes intensities reach such values and the total intensity of the excitation beams arrives at a maximum tolerable by most biological samples in a certain suppressed focal volume (40-nm suppressed focal scale in APIPD method), the DL correspondingly varies with exposure time, for example, DL values are 103 and 102 when exposure times are 20 ms and 200 ms respectively. 相似文献
76.
利用碱性条件下黄酮与Al3 生成粉红色络合物在可见光区510 nm处有最大吸收的特性,以芦丁为标样,采用分光光度法测定蜂胶超临界CO2萃取物中总黄酮含量,并与HPLC标准方法测定结果进行比较,发现各平行样的测定结果基本一致,最大偏差为268.38 mg/100 g,最小偏差为52.77 mg/100 g.该法简便快捷,结果相对准确,可作为蜂胶超临界CO2萃取物中总黄酮含量快速评估的一种方法. 相似文献
77.
78.
本文研究了super-Poincaré不等式在变换下的稳定性.利用自伴算子的谱分解性质,证明了当正定自伴算子L满足super-Poincaré不等式时,L的分数幂Lα也满足相应的super-Poincaré不等式,并讨论了相应半群的几种超有界性之间的关系. 相似文献
79.
本文采用了Gengsheng和Min(2003)提出的经验似然方法,基于一个新的方程对中值回归模型的参数进行统计推断,数值模拟的结果表明,本文所得到的参数估计结果比Gengsheng和Min(2003)的模拟结果更精确. 相似文献
80.