Thermal stability and reconstruction of nanoparticulate Au film on model molecular surfaces.

Thermally activated morphological reconstruction of nanoparticulate gold films deposited onto model molecular surfaces was investigated at 200 degrees C as a function of the annealing time. Results show a strong correlation of the spatial reorganization of the metallic particles to the surface chemistry of the underlying substrate. On the nonpolar surface, the thin nanoparticulate Au film dewets by the formation of randomly distributed nucleation holes. Two morphological reconstruction kinetics were observed. The first kinetics characterized by a sigmoid growth describes the time-evolution of the dewetted spots and particle size inside the spots, and the second corresponds to the number density of particles and displays an exponential decay with time. Ultimately our results show that even at temperatures well below the bulk metal melting point, nanoparticulate metal structures can undergo drastic morphological reconstructions which can irreversibly affect their functional properties and performance (catalysis, electronic).