Evaluation of light‐scattering and small‐angle x‐ray techniques using dilute dispersions of uniform polystyrene latices

Several light‐ and x‐ray‐scattering formulations were evaluated using polystyrene spheres having diameters near the wavelength of the employed light. While some error in the dimensions calculated using these equations is both expected and found, it is shown that these methods may still be useful for approximate or relative results. One of the purposes of this paper will be to estimate the applicability of these light‐scattering techniques to colloidal systems having sizes near the wavelength of light when only moderate accuracy is required. It is shown that the better diameter estimations are obtained by using (1) the maxima and minima that appear in the angular light‐scattering pattern, or (2) the Shull and Roess formulation adopted from small‐angle x‐ray theory