The beam of an electron microscope has been used by several workers to decompose solids but in most cases it was not possible to decide whether the decomposition was produced thermally or by the direct action of the electrons. For solid state reactions of the type solid to solid plus gas it is particularly important to determine the real cause as the direct evidence obtained in an electron microscope of the nuclei formation and growth of the solid product is necessary to test the validity of suggested mechanisms of decomposition. Sawkill (1) using a Metropolitan Vickers EM 3 microscope observed that single crystal silver azide flakes when decomposed by the electron beam produce silver part of which was ordered with respect to the original silver azide the remainder being completely disordered. On the evidence available at that time it was not possible to determine whether the decomposition was thermal or electronic.
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- 1.Sawkill,J.: Proc. roy. Soc. A 229, 135 (1955).Google Scholar