IMAGING PATTERN-FORMATION IN SURFACE-REACTIONS FROM ULTRAHIGH-VACUUM UP TO ATMOSPHERIC PRESSURES

Two optical methods that allow pattern formation to be investigated at an arbitrary pressure are here applied to image concentration pattern s of adsorbed species associated with heterogeneous catalytic reaction s. In contrast to most surface physical techniques, these methods are not restricted to high vacuum conditions and thus bridge the ''pressur e gap.'' With carbon monoxide oxidation on a (110) surface of platinum as an example, the coupling mechanisms responsible for spatiotemporal self-organization in surface reactions were followed from reaction-di ffusion control to the thermokinetic region, associated with phenomena not previously observed in pattern formation,