Low angle elastic light scattering study of diffusion limited aggregation

We have investigated the kinetics of the diffusion-limited aggregation of colloidal silica with low-angle elastic light scattering at 31 scattering angles covering the wave vector range 3.7 ƃ 102 cm-1 <q<3.3 ƃ 104 cm-1. We have studied both the asymptotic behaviour at larger q, which provides a measure of the clusters fractal dimension, as well as the roll-off region at small q, which gives information on the clusters size. Each set of data (scattered intensity vs. q vectors) has been analysed by means of a nonlinear iterative inversion scheme to provide the value of the number average gyration radius ⟨R⟩n which is found to grow in time with a power law tα. The exponent (average over a few runs) is α = 0.58 ± 0.02, consistent with the theoretical expectations. © 1988 IOP Publishing Ltd.