Integrated Intensities Using a Six-Circle Surface X-ray Diffractometer

The geometrical and resolution corrections are derived that occur in the measurement of the integrated intensities of surface diffraction rods for the case of a six-circle diffractometer. Since the six-circle geometry entails as special cases the five-circle and the z-axis diffractometers, the results are valid for these geometries as well. The derivations are valid for any incoming or outgoing angle of the X-ray beam, and are particularly important for measurements at large perpendicular momentum transfer. Expressions are derived for the integrated intensity from rocking scans, from stationary measurements and from reflectivity data. With all correction factors known, it is possible to derive the structure factors with a common scale factor from all these types of scans. It is expected that area detectors combined with stationary measurements will find widespread use in the surface X-ray diffraction community.