  In this paper we deal with the influence on absorption of the diffusive media
characteristics framing the problem in connection with the invariance property
(IP) of the mean path length. We show that the IP is an important issue that
regulates but not prevent the search of absorption maximization by scattering
characteristics. We find that the scattering may increase the absorption or
even be detrimental, depending on the geometry of the medium and the conditions
of its illumination.
