A new X-ray effect

Abstract

It is a remarkable but as yet imperfectly understood fact that crystalline graphite has a diamagnetic susceptibility many times greater than that of carbon in other forms, either by itself or in combination. In the hope of elucidating this phenomenon, we were led to make a careful study of the X-ray diffraction patterns of purified graphite, using a narrow pencil of the K radiation of copper, and taking special pains to avoid fogging of the plate in the vicinity of the primary beam, either by stray radiation or by photographic halation. The diffraction photographs obtained with powdered graphite in this way show a new and hitherto overlooked phenomenon (Fig. 1). We find a notable amount of scattered radiation in the area surrounding the primary beam, terminating sharply at the first diffraction ring, and reappearing with a much smaller though quite sensible intensity in the area between the first and second diffraction rings.