Neutron Topography of Vibrating Single Crystals of α-SiO2

INTENSITY changes in X-radiation diffracted by single crystals excited in different vibrational modes have been observed by X-ray topography1,2. Published topographs show the intensity distribution of X-rays diffracted by definite crystallographic planes as predicted by the Bragg condition. The photographic image intensity depends on the quality of a stationary single crystal; with a vibrating single crystal the vibrational mode may also be determined.