Measurement of the absorption coefficient of atmospheric dust

A method developed by previous workers for measuring the absorption coefficient of strongly absorbing powdered materials has been applied to samples of atmospheric dust in the 0.3-1.1-microm wavelength interval. This work, which is based on the Kubelka-Munk theory of diffuse reflectance, provides an estimate of the optical absorption coefficient. The corresponding imaginary refractive index is calculated from this value. Results are given for several samples of dry atmospheric dust collected in the desert of southern New Mexico. A typical value for the imaginary refractive index was found to be 0.007 at 0.6 microm, with little dependence on wavelength in the spectral range investigated. These results are found to be in good agreement with those of other workers obtained by different methods.