title: Nucleation of chemical waves at defects: a mirror electron microscopy study of catalytic CO oxidation on Pt(110).
abstract: Using mirror electron microscopy (MEM) as spatially resolving method the nucleation of chemical waves in catalytic CO oxidation on a Pt(110) surface was investigated in the 10(-5) mbar range. The waves nucleated at an electrically insulating impurity of approximately 15 microm diameter (the "defect") which most likely represents a diamond particle left over from the polishing process. Nucleation events are initiated by a dynamic process in a boundary layer of approximately 1 microm width between the defect and the surrounding Pt(110) surface. Depending on the parameter choice the fronts/pulses do not escape from the vicinity of the defect and later on die out or, in a supercritical nucleation, propagate across the surface. Asymmetric nucleation leads to spiral waves which remain pinned to the defect. The defect has a kind of steering effect causing chemical waves to collide exactly at the defect. This steering effect is evidently due to a distortion of the substrate lattice in the vicinity of the defect.
authors.affiliation: Institut für Physik und Physikalische Technologien, Technische Universität Clausthal, Leibnizstrasse 4, D-38678 Clausthal-Zellerfeld, Germany.
authors.forename: Han
authors.initials: H
authors.lastname: Wei
authors.forename: G
authors.initials: G
authors.lastname: Lilienkamp
authors.forename: R
authors.initials: R
authors.lastname: Imbihl