Microscopic aspects of pattern formation on surfaces.
Recent scanning tunneling microscopy (STM) work gives insight into microscopic processes of surface reactions that play a role for spatio-temporal pattern formation. STM allows to resolve adsorbed particles, follow their surface motion, and monitor reactions with other particles on the atomic scale. The data reveal pronounced deviations from the implicite assumptions of the reaction-diffusion equations traditionally used to model spatio-temporal patterns. In contrast to these descriptions, particles are often not randomly distributed, but cluster in islands because of attractive interactions, and particle hopping can be highly correlated. It is shown that such phenomena can even affect the macroscopic kinetics. The article also discusses a case where the atomic processes inside propagating reaction fronts could be resolved. Here particular strong interaction effects were observed, caused by hydrogen bonds between the reacting species. (c) 2002 American Institute of Physics.
Wintterlin
Joost
J
Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.