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91.
对时间成像理论进行简要研究. 利用电光相位调制器进行光脉冲压缩实验,并分别对基于电光相位调制和交叉相位调制的时间透镜组成的时间成像系统进行了仿真和讨论. 实验结果表明,基于电光相位调制的时间透镜组成的时间成像系统可以有效压缩光脉冲,但是该系统受到了孔径限制,压缩系数较小,分辨率较低. 进一步的仿真分析结果表明,基于交叉相位调制的时间透镜组成的时间成像系统不受孔径限制,能够获得更大的压缩系数和更高的分辨率,但是该系统的实现难度较大.
关键词:
光脉冲压缩
时间透镜
电光相位调制
交叉相位调制 相似文献
92.
We study the H+CH4/CD4→H2/HD+CH3/CD3 reactions using the time sliced velocity map ion imaging technique. Ion images of the CH3/CD3 products were measured by the (2+1) resonance enhanced multi-photon ionization (REMPI) detection method. Besides the CH3/CD3 products in the ground state, ion images of the vibrationally excited CH3/CD3 products were also observed at two collision energies of 0.72 and 1.06 eV. It is shown that the angular distribution of the products CH3/CD3 in vibrationally excited states gradually vary from backward scattering to sideways scattering as the collision energy increases. Compared to the CH3/CD3 products in the ground state, the CH3/CD3 products in vibrationally excited states tend to be more sideways scattered, indicating that larger impact parameters play a more important role in the vibrationally excited product channels. 相似文献
93.
运用密度泛函理论体系下的平面波赝势(PWP)和广义梯度近似(GGA)方法,计算研究了闪锌矿结构的ZnS晶体在不同的外界压强下的电子结构. 通过分析发现,随着外界压强的增大,晶格常数和键长在不断缩小,从S原子向Zn原子转移的电荷越来越少,Zn—S键的共价性逐渐增强,Zn原子和S原子的态密度都有不同程度的变化,而且还有向低能量移动的趋势. 当外界压强达到24GPA时,ZnS从直接带隙半导体变成间接带隙半导体,而且随着压强的增大,间接带隙逐渐变小,直接带隙逐渐增大.
关键词:
闪锌矿结构
态密度
能带结构
密度泛函理论 相似文献
94.
95.
96.
97.
Zi-Long Li Xing-Yue Tan Zhu-Feng Zhang Zhen-Yang Wang Xin-Heng Guo 《中国物理C(英文版)》2023,47(1):013102-013102-8
In this study, we systematically investigated two-pseudoscalar meson systems with the Bethe-Salpeter equation in the ladder and instantaneous approximations. By solving the Bethe-Salpeter equation numerically with the kernel containing the one-particle exchange diagrams, we found that the \begin{document}$ K\bar{K} $\end{document} ![]()
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, \begin{document}$ DK $\end{document} ![]()
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, \begin{document}$ B\bar{K} $\end{document} ![]()
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, \begin{document}$ D\bar{D} $\end{document} ![]()
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, \begin{document}$ B\bar{B} $\end{document} ![]()
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, \begin{document}$ BD $\end{document} ![]()
![]()
, \begin{document}$ D\bar{K} $\end{document} ![]()
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, \begin{document}$ BK $\end{document} ![]()
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, and \begin{document}$ B\bar{D} $\end{document} ![]()
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systems with \begin{document}$ I=0 $\end{document} ![]()
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can exist as bound states. We also studied the contributions from heavy meson (\begin{document}$ J/\psi $\end{document} ![]()
![]()
and \begin{document}$\Upsilon $\end{document} ![]()
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) exchanges and found that the contributions from heavy meson exchanges cannot be ignored. 相似文献
98.
H. S. Tan M. K. Han P. Y. Hu J. H. Zheng S. C. Ng H. Gong 《Applied Physics A: Materials Science & Processing》1994,59(3):245-251
An electron trap having an energy level of 0.14 eV from the conduction band edge was found in the bulk of copper-diffused VPE-grown n-GaAs0.6P0.4 by conventional DLTS measurements and by pulse-duration dependent capacitance amplitude measurements. The capture cross section at room temperature is about 1.0×10–21 cm2 and has a weak temperature dependence. These properties are attributed to a non-repulsive center having a capturing mechanism which involves multiphonon emission processes with hardly any lattice relaxation. Evolution of the spatial distributions of the traps with time under junction electric field were studied. The results suggest that the trap is positively charged and has a high diffusivity under electric field. The center can thus be identified as positively charged interstitial copper ion rather than some form of copper complexes. 相似文献
99.
A new numerical method is proposed to solve the Boltzmann equation. A frame is set up by using a discrete velocity approximation in the infinite velocity space, but by considering only those distribution function points which are not too small. The distribution function points may occur anywhere in the infinite discrete velocity space and are not constrained to a pre-specified region. A fourth-order finite difference is used for the convection terms. A Monte Carlo-like method is applied to the discrete velocity model of the collision integral. The effort of the method is proportional to the number of discrete points. Numerical examples are given for the full Boltzmann equation and results for some benchmark problems are compared with analytical or prior solutions. 相似文献
100.