The diffusive motion of adsorbates on crystal planes is studied by means of a lattice gas model with stochastic dynamics, in the disordered phase and at half coverage. The diffusion coefficient and the time-correlation functions measured in field-emission experiments are calculated. These correlation functions are shown to have the proper hydrodynamic power law decay at long times. It is pointed out that if experiments are done at times before the onset of the hydrodynamic regime the value of the diffusion coefficient obtained will be too small. Our results show also that correlations among the adsorbed particles persist for times longer than predicted by a hydrodynamical approximation.
Bibliographical noteFunding Information:
This work was supported by the University of Minnesota Research Fund and by the Materials Research Laboratory at the University of Chicago. E.O. acknowledges support from a NATO Fellowship provided by the Scientific and Technical Research Council of Turkey. We are extremely grateful to R. Gomer for discussions. We thank H. Metiu for a conversation on ref. [ 171.