REACTION FRONTS AND PULSES IN THE CO OXIDATION ON PT - THEORETICAL-ANALYSIS

A set of coupled nonlinear reaction-diffusion equations was formulated for the oxidation of CO on low-index plane Pt surfaces and solved for their spatiotemporal behaviour using continuation techniques and the method of global connections. A 2-variable model for Pt(111), consisting of the CO and O coverages as a function of time and space, gave rise to reaction fronts. In order to model the behaviour of Pt(111) or Pt(100) a third equation describing the respective adsorbate-driven phase transition had to be added. The resulting 3-variable system predicts extended regions of excitability, where pulses can be triggered. The front-respectively pulse - velocities as well as the critical radii for nucleation were computed and compared to experimental data where available.