It was found that the stretched-exponential relaxation which was commonly observed in disordered systems could be explained by time-dependent atomic diffusion. Relaxation was observed in the electronic properties of hydrogenated amorphous samples (a so-called H-glass) and reflected the equilibrium of localized electronic states. The relaxation was attributed to the motion of bonded H which exhibited dispersive diffusion with a characteristic power-law time dependence. A quantitative relationship between relaxation and diffusion was established.

J.Kakalios, R.A.Street, W.B.Jackson: Physical Review Letters, 1987, 59[9], 1037-40