Scattering from anisotropic particles: A challenge for the optical theorem?

摘要

The optical theorem is a very general law of scattering theory that has been discussed almostexclusively for spherically symmetric scatterers. In this work we present the extension to the case ofanisotropic scatterers, by treating explicitly the problem within the Rayleigh-Gans approximation. Workingformulas for the fluctuating components of the forward-scattering amplitude S_(VV)(0) andS_(VH)(0)are given,and a paradox concerning the applicability of the optical theorem is solved. While the S_(VH)(0)cannotinterfere with the incoming vertical polarized beam, we show that S_(VV)(0) fluctuates around a non-zeroaverage so to compensate at any instant for the integrated scattered intensity at both polarizations. Theresults are relevant for the design and interpretation of experiments of dynamic depolarized light scatteringin the forward direction. ~ae-mail:marco.potenza@unimi.it