Inelastic scattering of electrons by crystals. I. The theory of small-angle in elastic scattering
Inelastic scattering of electrons by crystals. I. The theory of small-angle in elastic scattering
复制标题
晶体对电子的非弹性散射。
DOI：
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发表时间：
1963
期刊：
影响因子：
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通讯作者：
A. Howie
中科院分区：
文献类型：
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作者：
A. Howie
研究了快电子在晶体中的传输的非弹性散射理论，当快电子用布洛赫波描述时，也考虑了布拉格反射。得到了小角度非弹性散射情况下波幅的解，结果表明，当等离子体激元激发中可能出现的长程相互作用势时，快电子的带间非弹性散射跃迁是被禁止的。这一结果可以解释最近电子显微镜观察到的使用弹性散射或非弹性散射电子获得的类似衍射衬度效应，并且还表明在衍射衬度理论中不需要考虑这种非弹性散射。该理论还预测了透射电子能谱中观察到的各个峰的强度的泊松分布。在厚晶体中，反常吸收效应很重要，发现布拉格衍射点周围散射强度的角分布包含不对称性，与实验观察结果定性一致。
The theory of inelastic scattering is studied for the transmission of fast electrons through crystals when the fast electrons are described by Bloch waves so that Bragg reflexion is also considered. Solutions for the wave amplitudes are obtained for the case of small-angle inelastic scattering and it is shown that interband inelastic scattering transitions of the fast electron are forbidden when the interaction potential is of the long range type which might arise in the excitation of Plasmon’s. This result would explain recent electron microscope observations of similar diffraction contrast effects obtained using elastically scattered or inelastically scattered electrons, and also shows that such inelastic scattering need not be considered in theories of diffraction contrast. The theory also predicts a Poisson distribution for the intensities of the various peaks observed in the energy spectrum of the transmitted electrons. In thick crystals, where anomalous absorption effects are important, the angular distribution of the scattered intensity round the Bragg diffraction spots is found to contain an asymmetry in qualitative agreement with the experimental observations.