Ripening of surface phases coupled with oscillatory dynamics and self-induced spatial chaos through surface roughening

Some pattern formation processes on single-crystal catalytic surfaces invol ve transitions between alternative surface phases coupled with oscillatory reaction dynamics. We describe a two-tier symmetry-breaking model of this p rocess, based on nanoscale boundary dynamics interacting with oscillations of adsorbate coverage on microscale. The surface phase distribution oscilla tes together with adsorbate coverage, and, in addition, undergoes a slow co arsening process due to the curvature dependence of the drift velocity of i nterphase boundaries. The coarsening is studied both statistically, assumin g a circular shape of islands of the minority phase, and through detailed L agrangian modeling of boundary dynamics. Direct simulation of boundary dyna mics allows us to take into account processes of surface reconstruction, le ading to self-induced surface roughening. As a result, the surface becomes inhomogeneous, and the coarsening process is arrested way before the thermo dynamic limit is reached, leaving a chaotic distribution of surface phases. (C) 1999 American Institute of Physics. [S1054-1500(99)01101-5].