Refraction Effects in Electron Diffraction

Abstract

OBSERVATIONS by Sturkey and Frevel¹ and Hillier and Baker² indicate that some rings in electron diffraction patterns from magnesium oxide and cadmium oxide smokes are double, and in one case (the 220 ring) it was suspected that there were five components contributing to the ring contour. Sturkey and Frevel suggested that refraction by the regularly shaped particles gave rise to the two components, although their data were not conclusive. Using the high-resolution system of the R.C.A. type E.M.U. microscope as a diffraction camera, we have attempted to find some feature of the diffraction by oxides of this type attributable to stoichiometric excess of the metallic constituent. We have obtained patterns showing resolution of details of fine structure of the reflexions, from which a complete interpretation of the phenomenon is possible.