Electrochemical nanostructuring by means of a scanning tunneling microscope (STM) tip is a promising field in electrochemistry. Up to now, several different types of techniques have been used for the generation of nanostructures with atomic dimensions. Paradigmatic examples are tip induced local metal deposition (TILMD) [[1]], where nanoclusters are generated by transferring material from the tip of a STM via a gentle mechanical contact; defect induced local metal deposition (DILMD) [[2]], where defects are generated on a metal surface through a change in the potential difference applied between the tip and the substrate surface, with the subsequent decoration of the defects produced on the surface; and supersaturation induced local metal
deposition (SILMD) [[3]], in which a metal (Me) from the electrolyte solution is deposited onto the uncovered part of a STM tip, and a potential pulse is applied to it, producing local supersaturation that leads to a nucleation and growth process.
In the present work, first steps are taken towards computer simulation of the atomistic mechanism taking place during the supersaturation induced local metal deposition method. Using a combination of stochastic Langevin dynamics (LD) and deterministic atom dynamics (AD), different results are observed depending on the model systems considered. For instance, when a profile of neutral diffusing species is used, atom dispersion over the whole electrode was found, whereas when charged species are introduced to the model system, a clear definite nucleation area was observed underneath the tip. The present computer simulations suggest that in the early stages of the process of cluster generation, the strong ion?ion repulsion may play an important role if the nanostructuring process is achieved in the nanosecond range. At the same time, a fast Co/Au surface mixing was observed in the top layer of the substrate in these short simulation times.
Acknowledgments: Financial support from CONICET, Agencia Córdoba Ciencia, Secyt UNC, and Program BID 1728/OC-AR PICT No. 06-12485 are gratefully acknowledged,
