INTEGRAL SCATTERING SECTION AND WAVE EXPONENT OF FRACTAL CLUSTERS

The integral scattering section and turbidity wave exponent w(T is sim ilar to lambda(-w)) of diffusion-limited (DLCA) and reaction-limited ( RLCA) fractal clusters were calculated in the Born approximation as a function of the size parameter X = kR(g) = (2pi/lambda)R(g) (R(g): rad ius of gyration). Three models of cutoff of the pair correlation densi ty function reported in the literature and a parametric model of the s tructural scattering factor proposed by M. Y Lin et al. were used in t he calculations. It was shown that the model with Gaussian correlation cutoff and the parametric model of the structural factor give almost identical results. The asymptotic properties of the scattering functio ns were examined for X < < 1 and X > > 1. It was shown that in the fra ctal condition of X > > 1, the wave exponent approaches 4 - D if D < 2 and approaches 2 if D > 2 (D is the fractal dimensionality). The effe ct of the size of the primary particles and angular aperture of the ph otodetector on the measured effective scattering sections and wave exp onent and their asymptotic behavior were investigated.