  Absolute X-ray reflectivity of chemically vapor deposited (CVD) diamond
single crystals was measured in the Laue geometry in the double-crystal
non-dispersive setting with an asymmetric Si beam conditioner crystal. The
measurements were supplemented by rocking curve topography. The measured
reflectivity curves are examined in the framework of Darwin-Hamilton approach
using a set of two independent parameters, the characteristic thickness of
mosaic blocks and their average angular misorientation. Due to strong
extinction effects the width of reflectivity curves does not directly represent
the average misorientation of the blocks. Two different sets of parameters were
found for the 111 asymmetric reflection in the two different scattering
configurations (beam compression and beam expansion). Analysis of the rocking
curve topographs shows that this discrepancy can be attributed to inhomogeneity
of the diamond crystal microstructure.
