DYNAMIC ORDER IN A SURFACE PROCESS

Under certain well-defined conditions (p//C//O, p//O//(//2//), T) the rate of catalytic oxidation of CO on a Pt(110) surface may exhibit sustained temporal oscillations with an autonomous frequency nu //0. Small amplitude modulation of p//O//(//2//) with frequency nu 2//p causes a variety of phenomena characteristic for systems of nonlinear dynamics which may be identified with temporal order and show formal similarities to spatial order of surface phases: Periodic behavior for certain rational numbers of nu //p/ nu //0 - corresponding to commensurate surface structures; quasiperiodic behavior characterized by an irrational ratio of the periods of perturbation and response - corresponding to incommensurate surface structures; and critical slowing down near the boundary of a transition to quasiperiodicity which has its counterpart in the critical fluctuations near a (spatial) phase transition.