Discussion about the X-ray beam divergence

Comparison of rocking curve widths before (bottom) and after (top) a second monochromator was added to collimate the X-ray beam

The plot at the right shows a comparison of the rocking curve width before and after using the second (220) silicon monochromator to narrow the energy width of the X-ray beam. The two images show the same region of the same crystal in the same orientation, so that the differences can be attributed to the improved definition of the beam.