A class of scattering media which generate Doppler-like frequency shifts of spectral lines

Abstract

It has been known for some time that under certain circumstances scattering from fluctuating media can generate shifts of spectral lines which are indistinguishable from those due to the Doppler effect, even though the source of the radiation, the scatterer and the observer are at rest with respect to each other. In this Letter a class of correlation functions of scattering media is introduced, each of which can generate such Doppler-like shifts. Red shifts as well as blue shifts can be produced by this mechanism, depending on the scattering geometry. We illustrate the results by an example involving diffusion in the presence of a random source.