Scattering of X-Rays by Bound Electrons

Abstract

THOUGH Bergen Davis and his collaborators (Phys. Rev., 23) have reported the detection by means of an ionisation chamber of the modified lines (over and above the Compton effect) produced by the scattering of a monochromatic beam of X-rays by carbon in a direction at right angles to the direction of propagation, Coster (NATURE, Aug. 10, 1929), Ehrenberg (Zeit. f. Phys., 53), and Kast (Zeit. f. Phys., 58) have failed to observe the same on the photographic plate. In a previous note to NATURE, it has been pointed out by me that a portion of copper Kα radiation in passing through carbon decreases its frequency by an amount equal to that of the Kα radiation of carbon. The accompanying photograph (Fig. 1) shows the effect of copper Kα radiation in passing through carbon, nitrogen, and oxygen. The known lines are marked as usual, while the new ones are shown by numbers. The white mark on the copper Kα line is due to the fact that a piece of aluminium was placed just in front of the photographic plate to decrease the blackness of the plate in this region.