Zhang Zaoli, Kaiser Ute
Materials Science Electron Microscopy, Ulm University, 89069 Ulm, Germany.
Ultramicroscopy. 2009 Aug;109(9):1114-20. doi: 10.1016/j.ultramic.2009.04.004. Epub 2009 May 8.
Modern transmission electron microscopes (TEM) allow utilizing the spherical aberration coefficient as an additional free parameter for optimizing resolution and contrast. By tuning the spherical aberration coefficient of the objective lens, isolated nitrogen atom columns as well as the Si-N dumbbells within the six-membered ring were imaged in beta-Si3N4 along [0001] and [0001 ] projections with a dumbbell spacing of 0.94 A in white atom contrast. This has been obtained with negative or positive spherical aberration coefficient. We clarify contrast details in beta-Si3N4 by means of extended image calculations. A simple procedure has been shown for pure phase imaging, which is restricted to linear imaging conditions.
现代透射电子显微镜（TEM）允许将球差系数用作优化分辨率和对比度的额外自由参数。通过调整物镜的球差系数，在β-Si₃N₄中沿[0001]和[0001]投影成像了孤立的氮原子柱以及六元环内的Si-N哑铃对，在白色原子对比度下哑铃间距为0.94埃。这是在负或正球差系数下获得的。我们通过扩展图像计算阐明了β-Si₃N₄中的对比度细节。已经展示了一种用于纯相成像的简单程序，该程序限于线性成像条件。
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