Specular reflection of X-rays by high-frequency sound waves

Abstract

The principle that a regularly stratified medium selectively reflects a monochromatic beam of radiation incident on it at the appropriate angle is well known and forms the basis for the X-ray analysis of crystal structure. The spots appearing in a Laue diffraction pattern are, of course, due to such selective reflections of the incident X-rays by the periodic stratifications which represent the static structure of the crystal. A specular reflection of X-rays may, however, also result from stratifications of density which are not static but dynamic in character, and which may be considered as equivalent to stationary sound waves of very high frequency. We have observed and studied numerous examples of this special kind of X-ray reflection, but will content ourselves here with giving a single illustrative example chosen for its simplicity.