BIFURCATION-ANALYSIS OF AN OSCILLATING SURFACE-REACTION MODEL

In the CO oxidation on a Pt(110) surface under isothermal gradientless conditions at low pressures, kinetic oscillations occur which have been studied in detail experimentally. A simple 3-variable model, based on the classical Langmuir-Hinshelwood mechanism and the adsorbate-driven 1 x 1 --> 1 x 2 phase transition of the Pt(110) surface, has been developed and analysed with the help of bifurcation theory. It explains the bistability and the occurrence of simple limit cycles. Extensions of the model in order to reproduce the more complex dynamics found in experiment are briefly discussed. With appropriate modifications the equations can model the dynamical behaviour of the Pt(100) and (111) surfaces, respectively.