SCATTERING OF UNPOLARIZED AND POLARIZED-LIGHT BY PARTICLE AGGREGATES OF DIFFERENT SIZE AND FRACTAL DIMENSION

The coupled dipole method has been used to study the light scattering properties of fractal aggregates. The importance of including dipolar interactions in calculating the total scattering and polarization prop erties of the aggregates is examined. For incident unpolarized light, both the intensity and degree of linear polarization of the scattered light are insensitive to interactions for aggregates of as many as 100 0 particles and with a fractal dimension as high as 2.5. Moreover, the form of the scattering function is not sensitive to fractal dimension . When the incident light is polarized, interactions may not be neglig ible. In particular, the magnitude and form of the S-34 element of the scattering matrix for aggregates depend strongly on their fractal dim ension. For a given fractal dimension and number of primary particles, this matrix element also varies for different aggregates generated by the same stochastic process; however, these differences within an agg regate type and size are smaller than those between aggregates of diff erent fractal dimension.