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. Author manuscript; available in PMC: 2014 Dec 1.
Published in final edited form as: Ultramicroscopy. 2013 Jun 8;135:10.1016/j.ultramic.2013.05.023. doi: 10.1016/j.ultramic.2013.05.023

Figure 5.

Figure 5

Example showing that a carbon-coated gold aperture does not become charged as the edge of the aperture is first brought close to the unscattered electron beam in the electron diffraction pattern. Nevertheless, a strongly charged patch is created if the unscattered electron beam is allowed to touch the edge. The left-hand panel shows the Thon rings when the unscattered electron beam is in the open area of the aperture, far from any edge. The middle panel shows that the radius of the Thon rings does not change as the edge of the aperture is brought close to the unscattered electron beam. The right hand panel, however, shows that the Thon rings are severely distorted by the patch potential created after the unscattered electron beam was allowed to briefly touch the edge.