Determination and correction of distortions and systematic errors in low-energy electron diffraction.
Determination and correction of distortions and systematic errors in low-energy electron diffraction.
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DOI：
10.1063/1.4774110
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发表时间：
2013-01
期刊：
影响因子：
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通讯作者：
F. Sojka;M. Meissner;Christian Zwick;R. Forker;T. Fritz
中科院分区：
文献类型：
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作者：
F. Sojka;M. Meissner;Christian Zwick;R. Forker;T. Fritz
我们开发并实现了一种算法来确定和校正低能电子衍射(LEED)图像中的系统失真。该程序原则上独立于设备的设计(球形或平面磷光屏与通道探测器)，因此适用于所有设备变体，称为常规LEED、微通道板LEED和光点轮廓分析LEED。基本的先决条件是具有已知结构和适当数量的衍射点的样品的校准图像，例如，Si(111)-7×7重建表面。该算法提供了一种可用于校正由相同设备产生的所有进一步测量的形式。具体而言，需要区分径向失真和非对称失真。此外，为了得到准确的晶格常数，有必要精确地知道电子的初级能量。通常，真实动能与LEED控制中设置的值之间会有偏差。在这里，我们介绍了一种比以前的研究更准确地确定这种能量误差的方法。对系统误差进行修正后，对未知样品的晶格参数测定，相对精度可达1%以上。
We developed and implemented an algorithm to determine and correct systematic distortions in low-energy electron diffraction (LEED) images. The procedure is in principle independent of the design of the apparatus (spherical or planar phosphorescent screen vs. channeltron detector) and is therefore applicable to all device variants, known as conventional LEED, micro-channel plate LEED, and spot profile analysis LEED. The essential prerequisite is a calibration image of a sample with a well-known structure and a suitably high number of diffraction spots, e.g., a Si(111)-7×7 reconstructed surface. The algorithm provides a formalism which can be used to rectify all further measurements generated with the same device. In detail, one needs to distinguish between radial and asymmetric distortion. Additionally, it is necessary to know the primary energy of the electrons precisely to derive accurate lattice constants. Often, there will be a deviation between the true kinetic energy and the value set in the LEED control. Here, we introduce a method to determine this energy error more accurately than in previous studies. Following the correction of the systematic errors, a relative accuracy of better than 1% can be achieved for the determination of the lattice parameters of unknown samples.