Equations are developed for Mie scattering by spheres (particles, bubbles, or voids) embedded in an absorbing medium. Computations demonstrate that under certain conditions the extinction-efficiency factor, Qext, can be less than the scattering-efficiency factor, Qs. In fact, Qext, as commonly defined, can be negative. Also, results are shown for the angular scattering distribution by a void, which indicate that the intensity of the backward-scattered light can be greater than the forward-scattered light.
W. C. Mundy, J. A. Roux, and A. M. Smith, "Mie scattering by spheres in an absorbing medium," J. Opt. Soc. Am. 64, 1593-1597 (1974)