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Figure 2
The Ewald constructions for the electron diffraction and X-ray cases are compared. The cross-hatched circle represents a reciprocal lattice within a limiting sphere of 1 Å resolution. The Ewald sphere for 12 keV X-rays with a wavelength of 1.0332 Å is represented as a complete circle, with the scattering vector s1 drawn at the 1 Å limit, forming an angle of 2θX = 62.2° from the incident beam direction along s0. At this scale, the Ewald sphere for 200 keV electrons, with a wavelength of 0.02508 Å, cannot be shown as a complete circle as it has a radius over 40 times greater. The equivalent scattering vector s1 for 1 Å diffraction forms an angle of only 2θe = 1.44° from the incident beam direction. It is worth noting that the reciprocal lattice is sampled along an almost planar surface, implying that data from a single image contain no information about the reciprocal-lattice dimension in the direction along the incident beam.

Journal logoSTRUCTURAL
ISSN: 2059-7983
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