An integration routine based on profile fitting with optimized fitting area for the evaluation of weak and/or overlapped two-dimensional Laue or monochromatic patterns

摘要

New software for the integration of weak and/or spatially overlapped diffraction patterns is presented. The program, named PROW (profile fitting for overlapped and weak data), uses box integration with an optimized summation area for strong nonoverlapped spots, and profile fitting with an optimized fitting area for weak and/or overlapped spots. The sizes of the integration areas are dynamically adjusted to find the best compromise between minimal bias resulting from statistical fluctuations of the X-ray background and maximal use of the information content in each diffraction spot. Deconvolution of spatially overlapped spots is performed by a standard least-squares procedure. The program is compatible with the Daresbury Laue software suite and with the DENZO package. It has been tested on several data-sets recorded on image-plate and CCD (charge-coupled device) detectors. Intensities extracted from very weak Laue data-sets containing as many as 60% overlapped spots were shown to be of sufficient quality to lead to an accurate structure refinement. Difficult monochromatic data-sets were also processed successfully, leading to a generally better compromise between reliability factors, redundancy and completeness than previously achieved. Concomitant improvement in atomic model refinement was also observed. [References: 35]