FINITE-SIZE POISONING IN HETEROGENEOUS CATALYSIS

The dynamics of a monomer-monomer and a monomer-dimer surface catalytic reaction are investigated. From the mean-field solution, finite systems eventually 'poison' at an exponential rate to a fully occupied, non-reactive state. For the monomer-monomer process, this poisoning is driven by concentration fluctuations of a diffusive nature, leading to poisoning times which vary as a power of the linear system size L. A comparison of the Monte Carlo simulations with the mean-field result suggests that the upper critical dimension for the monomer-monomer model is dc=2. For the monomer-dimer process, there is an effective potential that needs to be surmounted by fluctuations, leading to poisoning times which grow at least as fast as eL. This gives rise to an apparent reactive steady state.