Theory of transient grating experiments in disordered systems: anomalous percolation behaviour

Publisher Website
Google Scholar
Abstract
This work approaches the problem of incoherent diffusion or transport in disordered media as seen through transient grating experiments which allow a direct observation of the diffusion parameters. Using both the concept of the fractal space and the percolation theory in the critical region the authors predict the behaviour of the transient grating experiments in the two extreme cases when the interfringe is much larger or smaller than the correlation length of the disorder. They calculate the characteristic decay time of the transient grating as a function of the interfringe distance and of the critical exponents of the percolating system. In particular they show that when performed in the small-interfringe limit, the results of these experiments will directly reflect the properties of the fractal space of the diffusion through an anomalous interfringe dependence of the decay time of the transient grating.