Simple crystallography using protein diffraction images

The image below represents a 1-deg oscillation around the horizontal axis recorded for a protein crystal using CuKa radiation and a 300-mm Image Plate scanner set perpendicular to the primary beam at 220 mm from the crystal. The crystal is trigonal with the following cell constants: a=123, c=84 A.
Try to find the answer to each of the following problems:

1. Which of the crystal axes is nearly parallel to the primary beam?
2. Approximately, how are the other crystallgraphic axes oriented relative to the Image Plate at this crystal orientation?
3. What is the angular deviation of the axis in question 1. from the primary beam?
4. Try to estimate the crystal mosaicity.

Back to CBB home page

Last update: June 4, 1998