Optical structure factor measurements of soot particles in a prmixed flame.

We have measured the scattered-light intensity as a function of the scattering angle for light scattered from soot particles in a premixed methane/oxygen flame. This yields the optical structure factor for the soot particles. We find that the structure factor shows the soot particles to have a morphology consistent with a fractal interpretation with a fractal dimension in the 1.6 </= D </= 1.8 range and a radius of gyration that increases with the height above the burner. The structure factor may also show the effect of the finite monomer size of the soot clusters.