QUASI-ELASTIC INCOHERENT-SCATTERING IN FRACTAL SYSTEMS

The diffusive behavior of particles can be studied with the help of qu asielastic light or neutron scattering. Diffusion within a fractal spa ce does not follow the normal law [r(2)] similar to t, r being the dis placement in time t. In this paper we study quasielastic scattering in fractal spaces and try to predict new features which may be observed experimentally. Examples of such systems may be the AgI percolation cl usters in glassy AgI berate and phosphate superionic conductors, gel-t ype protonic conductors, and biological systems. For such fractal syst ems our calculated line shape of scattered intensity, S(k,omega), is f ound to be oscillatory in nature unlike the Lorentzian centered at ome ga=0, for normal diffusion. The maximum scattered intensity S(k,0) has a power-law dependence on k. Also the half width at half maximum is f ound to be independent of k.