Measurement of X-ray integrated intensity with diagnostic identification of peak and background

Recognition of the intrinsic two-dimensional nature of the intensity distribution, I(ω, 2θ), of a Bragg X-ray reflexion allows identification of the spectral dispersion of the source and the fragment/mosaicity (f/m) distribution of the specimen small crystal. With this information as a basis for the measurement of integrated intensity, the spectral band (wavelength truncation) can be maintained constant from reflexion to reflexion and the real extent of the f/m distribution established by reference to a signal/noise index. With this procedure, the separation of peak from background is placed on an objective basis not feasible with the conventional analysis of the one-dimensional reflexion profile. The method is demonstrated using the ω, 2θ slice scan procedure [Mathieson (1982). Acta Cryst. A38, 378-387] but is also relevant to the use of linear position-sensitive detectors.