Reflection of X-rays from Rock Salt

Abstract

Reflection of $X-\mathrm{rays}$ from Rock-salt Crystals.—By means of the double spectrometer arrangement previously used in studying the reflection from calcite, a narrow beam of nearly homogeneous rays from one crystal was reflected from a second crystal. The two natural cleavage surfaces used were obtained by splitting a good clear specimen. The rocking curves are irregular and more than 50 times as wide as corresponding curves for calcite, while the per cent. reflection at parallelism of the surfaces was much less than for calcite, being only 10 for 3° grazing angle and 5 for 7°. Polishing the reflecting surfaces increased the curve width somewhat but washing with water restored the surfaces to their original condition. By interposing a third slit between the crystals and moving it across the beam more detailed information was obtained as to the position and character of the imperfections in the crystal surface. Another selected pair of freshly split surfaces gave similar results, except that the per cent. reflection at parallelism was about twice as great.