New method in elastic light scattering from Mie-particles

Abstract

Particles in the size range 200 < D < 2000 rim have enough information in their scattering function for a general interpretation procedure. The experimenter is faced with two basic problems. There is an essential loss of information caused by the cutoff, and the scattering theory of Mie has to be used for the description of the scattering process. It has been previously proved that the interpretation of scattering results is much easier in real space (distance distribution function p(r)) than in reciprocal space. It is shown to what extent it is possible to apply the corresponding techniques to light scattering data. There exists no analytical method for the transformation of Mie scattering data into real space. Therefore we have used Fourier transformation as an approximation. The results show that this approximation gives reasonable results for ideal data as well as for data with up to 10 % statistical noise. The main influence of the Mie contribution are oscillations outside the maximum particle dimension. The shape of the part up to the maximum dimension containing the important information about the structure is nearly unchanged. The principles of the method and the application to spherical particles have been published recently [1. Coll Interf Sci (1985), 105,577-585]. We can now present results for nonspherical and inhomogeneous particles. The radial polarizability profile can be calculated by a convolution square root technique, even for particles with imperfect symmetry. Initial results for polydisperse systems show that this method could be superior to the particle sizing methods using quasi-elastic light scattering in the size range mentioned above. Authors' address: O. Glatter University of Graz Graz, Austria