Traveling Interface Modulations in a Catalytic Surface Reaction

M. RAFTI, H. UECKER, F. LOVIS, V. KRUPENNIKOVA AND R. IMBIHL

Oldenburgo

Congreso; Dynamics Days Europe 2011; 2011

Dynamics Days Europe 2011

The surface reaction of NH3 + O2 on a Rh(110) surface was studied underUltra High Vacuum conditions (pressures  1  10􀀀5 mbar, and tempera-tures between 300􀀀900 K). By means of Photoemission Electron Microscopy(PEEM), local values of surface work function were recorded during reaction,which in turn allows to identify up to some extent the adsorbate coveragesand surface structure of dierent regions of the catalyst.Numerous spatiotemporal structures were observed such as traveling pulses,spiral waves and front-like transitions between dierent regimes. In par-ticular, the appearance of segregated areas with dierent phase structureand oscillating limits ("Traveling interface modulations"), is discussed in thepresent communication. A phenomenological model that allows an interpre-tation of the experimental features is proposed.The observed behavior is attributed to diusional mixing of two spatiallyseparated adsorbates causing an excitability which is strictly localized to thevicinity of the interface of the adsorbate domains.