  Many applications of electromagnetic scattering involve particles immersed in
an absorbing rather than lossless medium, thereby making the conventional
scattering theory potentially inapplicable. To analyze this issue
quantitatively, we employ the FORTRAN program developed recently on the basis
of the first-principles electromagnetic theory to study far-field scattering by
spherical particles embedded in an absorbing infinite host medium. We further
examine the phenomenon of negative extinction identified recently for
monodisperse spheres and uncover additional evidence in favor of its
interference origin. We identify the main effects of increasing the width of
the size distribution on the ensemble-averaged extinction efficiency factor and
show that negative extinction can be eradicated by averaging over a very narrow
size distribution. We also analyze, for the first time, the effects of
absorption inside the host medium and ensemble averaging on the phase function
and other elements of the Stokes scattering matrix. It is shown in particular
that increasing absorption significantly suppresses the interference structure
and can result in a dramatic expansion of the areas of positive polarization.
Furthermore, the phase functions computed for larger effective size parameters
can develop a very deep minimum at side-scattering angles bracketed by a strong
diffraction peak in the forward direction and a pronounced backscattering
maximum.
