Crystal lattice dimensions measured directly from electron micrographs of thin crystallites may not be accurate. The reason is that reciprocal lattice points are elongated because the crystallite is normally thin in the direction of view. Optical diffraction patterns from electron micrographs of these thin specimens may therefore be slightly skewed relative to true reciprocal lattice planes. The result is a bias toward shorter observed lattice translations in the micrographs. The projection theorem combined with the elongation of reciprocal lattice points can be used to evaluate these variations. A method for correcting for the skewing is described and test data are presented to show the magnitude of this effect.
Bibliographical noteFunding Information:
funds (National Science Foundation, B1KS 74-03397 and National Institutes of Health, GM-13925). We also acknowledge the assistance of Mr R. Wrenn in the construction of Figure 1.
We are indebted to Dr Stephen Harrison for his helpful comments during the preparation of this manuscript. We acknowledge the predoctoral support from the National Science Foundation for one of us (D. H. O.) and the National Institutes of Health (GM-02016) for support for one of us (M. L. C.). We are also grateful t~ these two agencies for research