ABSORPTION-COEFFICIENT-DETERMINATION METHOD FOR PARTICULATE MATERIALS

A method is presented for determining the optical absorption coefficie nt, or the imaginary refractive index, of particulate material that ha s been collected from aerosols or hydrosols by means of filtration. Th e method, based on the Kubelka-Munk theory of diffuse reflectance, is nondestructive and requires no other knowledge of the sample than the amount present, the specific gravity, and an estimate of the real inde x of refraction. The theoretical development of the method is discusse d along with an analysis of photometric and gravimetric errors. We tes t the method by comparing results obtained for powdered didymium glass with measurements made before the glass was crushed. An example of th e method's application to the determination of the absorption coeffici ent of atmospheric dust at LTV, visible, and near-IR wavelengths is al so presented.