Stochastic resonance in the absence and presence of external signals for achemical reaction

A catalytic reduction of NO with CO on Pt(100) surface is adopted to study its response under random perturbation. Noise-induced oscillations and nois e-induced frequency shifts have been observed when the system works in the vicinity of the oscillatory region and meanwhile is subjected to random mod ulation of its feeding speed. Stochastic resonance behavior can be recogniz ed from the noise-induced peak in the power spectrum even though in the abs ence of external signals. The numerical results have been obtained near sup ercritical Hopf bifurcation points, but are not confined to the classificat ion of bifurcation. When the system falls into bistable regions, noise can help an external weak signal to induce state-to-state transitions and also shows a stochastic resonance behavior except for the case that the system h as an isolated bifurcation scheme. (C) 1999 American Institute of Physics. [S0021-9606(99)70706- 3].