Electron ptychography. I. Experimental demonstration beyond the conventional resolution limits
Electron ptychography. I. Experimental demonstration beyond the conventional resolution limits
复制标题
电子叠印术。
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
J. Rodenburg
中科院分区：
文献类型：
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作者：
P. Nellist;J. Rodenburg
描述了电子衍射的相位问题的解决方案，其允许无像差的Si 110 nm的原子分辨率图像，显示预期的哑铃对比度，以3倍的点分辨率和2.5倍的信息限制的扫描透射电子显微镜（STEM）的分辨率重建。所需的数据集包括作为照明探头位置的函数记录的相干微衍射图案和图像重建的方法超出了传统的分辨率限制，使用此数据集进行了描述。使用实验数据集的固有冗余，重建图像的准确性进行检查，并确定影响它的实验缺陷。据发现，孔径充电，在检测系统中的失真，是错误的主要来源。作为这种方法的相位恢复的一个额外的应用程序，衍射束相位的电子，已经失去了能量，通过激发等离子体激元相比，在石墨的试样中的弹性散射电子。在这种方法的限制内，发现在束相位中没有差异，支持已经经历多次弹性和非弹性散射的电子在更高角度处主导等离子体激元损失散射的观点。
A solution to the phase problem of electron diffraction is described which allows an aberration-free atomic resolution image of Si〈110〉, showing the expected dumbbell contrast, to be reconstructed at a resolution of 3 times the point resolution and 2.5 times the information limit of the scanning transmission electron microscope (STEM) used. The data set required consists of coherent microdiffraction patterns recorded as a function of illuminating probe position and the method of image reconstruction beyond the conventional resolution limits using this data set is described. Using the inherent redundancy in the experimental data set, the accuracy of the reconstructed image is examined and the experimental imperfections that affect it are identified. It is found that aperture charging, compounded by distortions in the detection system, are the major sources of error. As an additional application of this method of phase retrieval, the diffracted-beam phases of electrons that have lost energy by exciting a plasmon are compared with those of elastically scattered electrons in a specimen of graphite. Within the limits of this approach, it is found that there is no difference in the beam phases, supporting the view that electrons that have undergone multiple elastic and inelastic scattering dominate the plasmon-loss scattering at higher angles.