Session EC17 - Scattering From Particles and Surfaces.
ORAL session, Monday morning, March 22
Room 263W, GWCC
We are testing the theory of optical scattering cross sections of fractal aggregates. To do this we look at laser light scattering from an aggregating system of small (14nm) polystyrene spheres suspended in water. Through the use of dynamic light scattering (DLS) we are able to size particles in the colloid and measure the intensity of scattered laser light from them as they aggreagte from single spheres to aggregates of over 100 spheres. This data is then analyzed using the data obtained from aggreaged spheres as a calibration. According to light scattering theory, at a given scattering angle the normalized scattered intensity should be proportional to the hydrodynamic radius to the fractal dimension (R_m ^D). Using static light scattering techniques to separately measure the fractal dimension D, we have found that, within the Rayleigh limit, the optical scattering cross section of fractal aggregates appears to conform well to theory.