TEST OF STATIC STRUCTURE FACTORS FOR DESCRIBING LIGHT-SCATTERING FROM FRACTAL SOOT AGGREGATES

We compare several static structure factors for light scattering from fractal aggregates. The variation between these structure factors is a result of different cutoff functions for the cluster density correlation function. Light scattering data obtained from soot aggregates in a premixed CH4/O2 flame are fit with three representative structure factors. Fractal dimensions determined from these fits under the assumptions of a monodisperse size distribution are all unsatisfactory. Inclusion of a scaling cluster size distribution yields good fits to structure factors derived from correlation functions with cutoffs faster than exponential, the exponential structure factor yielding a poor fit. A Gaussian cutoff was found to work the best.