CATALYSIS AT SINGLE-CRYSTAL PT(110) SURFACES - GLOBAL COUPLING AND STANDING WAVES

Recently various types of spatiotemporal concentration patterns have b een observed in experimental studies of catalysis on single-crystal su rfaces. One of the most interesting phenomena among these is the stand ing-wave pattern which has been seen in CO+O2-->CO2 on Pt(110). A kine tic model involving surface reconstruction has been proposed for this system by Eiswirth, Krischer, and Ertl [Appl. Phys. A 51, 79 (1990)]. Here, we add spatial-coupling terms due both to CO diffusion and to gl obal gas-phase fluctuations and we study the possible wave patterns in this set of reaction-diffusion equations. We argue that the standing waves may be due to a self-induced parametric driving mechanism. Our a nalytical results as well as our numerical simulations are qualitative ly consistent with the experimental findings.