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O: Oberflächenphysik

O 7: Surface reactions I

O 7.6: Vortrag

Montag, 27. März 2006, 12:30–12:45, WIL C207

Mass transport with pulses in an excitable surface reaction: Rh(110)/K/NO + H2 — •Hong Liu¹, Ling Zhou², Sebastian Günther³, and Ronald Imbihl¹ — ¹Institute for Physical Chemistry, Hannover University, Callinstr. 3-3a, D-30167 Hannover, Germany — ²Division of Engineering and Applied Sciences, Harvard University, Pierce Hall, 29 Oxford St., Cambridge, MA 02138, USA — ³LMU München, Department Chemie, Butenandstr.11 E, 81377 München, Germany

Pattern formation in the NO + H2 reaction on a Rh(110) surface predosed with potassium has been studied with photoelectron emission microscopy (PEEM), low energy electron microscopy (LEEM), and with scanning photoelectron microscopy (SPEM) at ELETTRA. With the addition of potassium the NO + H2 reaction retains its excitability, but one finds now that the pulses are transporting potassium. In areas where pulses collide, a strong enrichment of K takes place. Under certain conditions stationary patterns develop in which the K-enriched areas form a macroscopic network. Compared to the unpromoted system the direction of the traveling wave fragments has been rotated by 90^∘. A mathematical model is proposed which explains qualitatively the main observations.