X-Ray Three-Beam Diffraction by Diamond Single Crystals

We have studied the effect of the real structure of diamond single crystals on variations of the intensity profiles of the Kossel lines at the intersection of them. The intensity profile of intersecting lines characterizes an anomalous X-ray transmission and is not a simple sum of individual lines. The revealed effect is most sharply defined for type 1b diamond crystals (having a nitrogen impurity in the lattice). The experimental data on the X-ray diffraction by diamond single crystals qualitatively fit the theoretical calculations of the X-ray diffraction by a single crystal of the cubic syngony in the three-beam region when an ultrasonic wave passes through the crystal. The anomalous distribution of the intensity over the three-beam region is attributed to the periodic deformation of the diamond lattice caused by a selective absorption of a nitrogen (boron) isomorphic impurity by a growing crystal.