Scattering curve and radius of gyration of a straight chain of identical spheres

The angularly averaged scattering intensity and the radius of gyration of a straight chain of N equal spheres have been derived. The intensity becomes equal to zero at the same points where the intensity of the constituting sphere vanishes. The property holds also for a `particle' formed of N equally sized and non-overlapping spheres with different electron densities. The radius of the spheres can be determined from the positions of the zeros. The number of the spheres can be obtained from the extrapolated zero-angle intensity or from the radius of gyration in the case of linear chains.