A modified method for slit-length collimation corrections in small-angle X-ray scattering

Two improvements have been made in a method which was previously developed [Schmidt, P. W. (1965). Acta Cryst. 19, 938–942] for correcting small-angle X-ray scattering curves for the effects of the length of the collimating slits. In both the original and modified correction methods, the scattering data are assumed to be measured at integral multiples of an angular increment Δ. With the earlier procedure, if the smallest measured intensity was recorded at an angle j0Δ, where j0 is an integer, the smallest angle at which corrected intensities could be computed was (j0 + 2)Δ. The correction method has been modified to permit evaluation of corrected intensities beginning with the angle j0Δ, thus avoiding the loss of the information contained in the intensities measured at the two smallest angles. In addition, a technique has been developed for estimating the uncertainty in the corrected intensity when all measured intensities are recorded for equal counting times and the uncertainty in the measured intensity is assumed to be proportional to the square root of the number of counts recorded.