Electroless deposition dynamics of silver nanoparticles clusters: A diffusion limited aggregation (DLA) approach

Silver nanoparticles (NPs) aggregates with an overall size in the nano meter range were fabricated employing non conventional electroless techniques. The structure of the aggregates was analyzed through direct SEM and AFM imaging; space-frequency based variables, including fractal dimension, were extracted in order to yield a quantitative measurement of the topography of the systems at study. These observations were explained within the framework of diffusion limited aggregation (DLA). DLA theory founds upon the paradigm that, in the limit of very fast chemical reactions, diffusion is the sole driving force that regulates the dynamics of aggregation of NPs. The mathematical model confirmed the experimental findings whereby the fractal dimension of the clusters is size dependent, that is, larger systems are more discontinuous than smaller. The model would also predict that, under certain conditions, a characteristic length exists beyond which the fractal dimension is constant. DLA theory is consistent and predictive in nature, and may be of valuable help in designing devices that utilize rough metal surfaces and the derived effects thereof, including SERS substrates.