Transmission of X-Rays Through Calcite in Laue Diffraction

Precise measurements of the shape of the transmitted intensity curve in the case of Laue diffraction in high quality calcite have been made at a wavelength of 0.708 A. The range of crystal thicknesses investigated, from 0.05 cm to 0.620 cm, clearly shows the transition from extinction to anomalous transmission. Values of the crystal absorption coefficient at the diffracting position are given. For the thick crystal case, for example, the absorption coefficient at anomalous transmission for a 0.563-cm crystal was 6.61 ${\mathrm{cm}}^{-1\mathrm{}}$ compared with a normal absorption coefficient value of 22.0 ${\mathrm{cm}}^{-1\mathrm{}}$. Comparison of the data with theoretical results of Hirsch, Ramachandran and Kartha, and Zachariasen shows reasonable agreement.