Fractal characterization of the distribution of reactive sites over a rough catalyst surface

The amount of reactive sites, usually dispersed noble metal atoms, on the top of a catalyst rough surface is characterized within the framework of fractal geometry. The problem is reduced to evaluating properties of a fractal set built on a self-affine profile. Numerical simulations are used to generate both support and different amounts of dispersed atoms. Three different parameters (local and global fractal dimension and roughness exponent) are used to analyze profiles obtained by three different processes. Results indicate that the quantitative characterization of dispersed atoms follows from the direct evaluation of the local fractal dimension. This, in turn, is achieved after a simple adaptation of an optimized box-counting algorithm.