High-order multiple diffraction in GaAs

Multiple diffraction patterns of a single crystal of GaAs have been recorded with Cu Kα₁ radiation. Calculations indicated that 19 peaks, all involving reflections with odd indices, should be observed in the 45° asymmetric angular range of the multiple diffraction pattern. All these were observed and indexed. In addition, six sharp but barely detectable intensity minima, were observed in the background. These result from one eight-beam, one six-beam, and four four-beam interactions, all involving reflections with even indices. The geometry of these interactions is discussed and their integrated intensities have been calculated. These show fair agreement with the corresponding measured intensities.