Intensity corrections for one-dimensional structure determination

Procedures for correcting experimental diffraction intensities in the small-angle region for the determination of one-dimensional structures are presented. The diffraction patterns in question consist of meridional streaks which are transversely broadened due to: (1) finite fibril radius, (2) imperfect fibrillar orientation, (3) lamellar curvature or (4) instrumental broadening. Three methods are developed and compared for obtaining corrected intensities in the presence of these effects. One method uses direct integration over all reciprocal space. Two complementary techniques involve correction of integrated layer line or meridional peak intensities; the correction factors are shown to be the transverse integral widths of the layer lines, suitably modified for instrumental broadening.