Rocking-Curves by Transmission of the X-Ray Beam Through Calcite Crystals

With a two-crystal spectrometer, the rocking-curves for calcite crystals in the (1, -1) position have been observed at the wave-length 0.208A (W $K{\alpha }_1$) for an arrangement in which the x-ray beam is transmitted through the body of the crystal and reflected from a family of internal Bragg planes. The width of this transmission rocking-curve has no obvious relation to the thickness or to the optical quality of the crystal. The narrowest width observed is of the same order of magnitude as that generally obtained by reflection from untreated cleavage surfaces. Etching the faces of two crystals made a considerable change in the rocking-curve width, but did not reduce this width to a value comparable to that obtained by reflection from etched faces. The results of the etching treatment are discussed.