Millimeter-wavelength investigation of fibrous aerosol absorption and scattering properties

The measurements here are used to examine agreement with a recently developed theory for long-wavelength fibrous aerosol attenuative properties (extinction and components absorption, scattering). This is intended to be the final phase of a long and systematic examination of the theory's key features. In this case the parameters are high conductivities coupled with a broad range of fiber diameters. It is clear that there is a limit on the extinction efficiency or effective extinction cross section per unit fiber volume. This limit is represented by the fiber diameter of translucency, that is, the diameter at which the fiber is not completely opaque to the electromagnetic energy. The transition is approximated by the classical skin depth of the fiber. Above this diameter the peak extinction efficiency decreases with an increase in diameter at approximately the same rate for all conductors. The scattering resonance producing this peak becomes stronger as the diameter increases. Our data confirm that for fiber diameters below the skin depth the character of the attenuation is that of absorption. (C) 2004 Optical Society of America.