Determination of parameters of surface mass transport from morphological changes of beaded thin films

Theoretical and experimental investigations of the time dependence of the effective thickness and shift of the boundary of beaded thin films are presented, supposing evaporation or diffusion into the substrate. In addition to evaporation and (bulk and surface) diffusion, the role of boundary reactions at the perimeter of beads as well as at the surface layer-bulk interface are taken into account. It is shown that the time dependence of the effective thickness and shift of the boundary is different for diffusion-interacting ensembles and for isolated particles, and is determined also by the relative magnitudes of the diffusion and interface reaction currents. Our paper has a review character in the sense that all special cases treated before by different theoretical models can be obtained as limiting cases from our theory. Furthermore, the description of the time dependence of the shift of the boundary for diffusion dissolution is original. Using the example of Cu beaded films on Mo as well as Ag on alumina surfaces, it is illustrated that from simultaneous experimental measurements of the effective thickness and the shift of the beaded film one can determine all the parameters controlling the surface mass transfer.