Fluctuations during catalytic CO oxidation on different crystal planes of a Pt field emitter

Fluctuations during catalytic CO oxidation on the (100), (111) and (113) pl anes of the [100]-oriented Pt field emitter tip are studied by FEM (field e lectron microscope). Intensity profiles and local time series are obtained by digitizing the image brightness in a rectangular probing window oriented along the [110]-direction. From the local time series the probability dens ity distributions as well as the auto- and cross-correlation functions are computed. The results demonstrate that the fluctuation behavior is quite di fferent on the different facets of a field emitter tip. On the facets studi ed here, the fluctuations observed in the monostable and in the bistable re gion of the reaction exhibit substantial differences in the degree of time- and spatial correlation.