Extra Rings in Electron Diffraction Patterns

Abstract

MARK, Motz and Trillat¹ have shown that traces of grease can give rise to extra rings in electron diffraction patterns from metal films. In agreement with them, we have found that the spacings of these grease rings are as given in col. 1 of the accompanying table, and are independent of the nature of the metal substrate. The spacings of extra rings obtained by heating a metal in a gas are, however, quite different in that they depend not only upon the metal but also upon the gas and the nature of the heat treatment². Thus, for example, we have obtained different extra ring systems by drawing gold leaf through a Bunsen flame (col. 2) and by heating in oxygen at 540° C. during 30 minutes (col. 3). The reproductions 1–6 are from the corresponding electron diffraction patterns.