Experimental determination of scattering matrices of randomly oriented flyash and clay particles at 442 and 633 nm

We present measurements of the scattering angle distribution of the whole s cattering matrix for randomly oriented particles of three mineral samples: fly ash, green clay, and red clay at 442 and 633 nm. Fly ash consists of ag gregates of nearly spherical particles while green clay and red clay partic les represent irregular compact particles. We compare the measured results for fly ash with an experiment ally determined average scattering matrix wh ich is based on measurements for a broad selection of irregular mineral aer osol particles. We find that the scattering matrix of our polydisperse samp le of aggregates of nearly spherical particles differs considerably from th at of compact particles. In addition, the angular distribution of the eleme nts of the scattering matrix (except F-22(theta)/F-11(theta)) for fly ash p articles seem to be dominated by the single monomers. The effects of small differences in composition on the scattering behavior have also been studie d by comparing our experimental results for green clay particles with those obtained by Volten et at. [2001] for red clay particles at the same wavele ngths.