Variations of LEED intensities with angle of incidence and the influence on spot profiles.
Variations of LEED intensities with angle of incidence and the influence on spot profiles.
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LEED 强度随入射角的变化以及对光斑轮廓的影响。
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
King
中科院分区：
文献类型：
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作者：
Held;Wander;King
我们对入射电子束方向的变化对Ni{111}和p(2\ifmmode\times\else\texttimes\fi{}2)C-Ni{111}表面低能电子衍射（LEED）强度的影响进行了系统的理论研究。极化入射角在5\ifmmode^\circ\else\textdegree\fi{}量级变化时，观测到较大的强度调制，当极化角变化约10\ifmmode^\circ\else\textdegree\fi{}\char21{}15\ifmmode^\circ\else\textdegree\fi{}后，理论I-V曲线之间的R因子比较上升到1.0（即不相关）。这些数据可以作为一组独立的I-V曲线来增加LEED分析的能量范围。在非正态入射方向收集数据的另一个好处是，多个r因子极小值可以通过在极角上改变20\ifmmode^\circ\else\textdegree\fi{}\char21{}30\ifmmode^\circ\else\textdegree\fi{}来移位或消除。然而，当极角小于40\ifmmode^\circ\else\textdegree\fi{}时，对表面原子横向位置的灵敏度没有明显的提高。我们还研究了通过入射方向扫描获得的数据对被测光斑剖面的可能影响。在一定的角度扫描范围和能量下，等入射角下的分裂光斑的相对卫星强度存在严重差异，光斑形状会进一步展宽和畸变。
We have performed a systematic theoretical study of the effects of variations in the direction of the incoming electron beam on low-energy electron-diffraction (LEED) intensities for the surfaces Ni{111} and p(2\ifmmode\times\else\texttimes\fi{}2)C-Ni{111}. Large intensity modulations are observed for variations of the order of 5\ifmmode^\circ\else\textdegree\fi{} in the polar angle of incidence, and the R factor comparison between theoretical I-V curves rise to 1.0 (i.e., no correlation) after varying the polar angle by about 10\ifmmode^\circ\else\textdegree\fi{}\char21{}15\ifmmode^\circ\else\textdegree\fi{}. Such data can be used as an independent set of I-V curves to increase the energy range of LEED analyses. Another benefit of collecting data at off-normal incidence directions is that multiple R-factor minima can be shifted or eliminated by changes of 20\ifmmode^\circ\else\textdegree\fi{}\char21{}30\ifmmode^\circ\else\textdegree\fi{} in the polar angle. However, we could not see a clear improvement in the sensitivity towards the lateral positions of surface atoms for polar angles below 40\ifmmode^\circ\else\textdegree\fi{}. We have also studied possible effects on measured spot profiles for data taken by scanning through the incidence direction. Serious differences in the relative satellite intensities of split spots which are equal at constant incident angle and additional broadening and distortions of spot shapes could be found for certain angular scan ranges and energies.