Pattern Formation in a Surface Reactions with Global Coupling

Monday, May 11, 1998 - 11:00am - 12:00pm
Keller 3-180
H.h. Rotermund (Fritz-Haber Institut)
Dynamic processes on surfaces, like the Pt - catalyzed CO-oxidation, can be described by a set of simple reaction-diffusion equations. For a certain range of the control parameters which are the partial pressures of the reactants and the temperature of the sample pattern formation like spiral waves, target patterns or solitary waves can be observed. When global coupling via the gas phase is introduced strong temporal oscillations may occur, sometimes exhibiting spatio-temporal patterns like standing waves, their period doubling and chaotic behavior. The mentioned patterns were found under isothermal conditions. Of course, when increasing the reaction pressure, due to the exothermic nature of the CO-oxidation, also temperature patterns can be explored, observable with a sensitive InfraRed (IR) camera. A short video will demonstrate the great richness of spatio-temporal pattern formation for a simple surface reaction.