Atomic level surface studies of nanotube field emission cathodes

Carbon nanotubes are of interest due to their unusual chemical and electrical characteristics and have been suggested for use in a wide variety of applications including field emission cathodes. Their small diameter and conductive and semiconductive properties may make them potentially useful field electron emitters. However, there are indications that they, like most field emitters, are sensitive to the vacuum environment in which they operate. In order to understand this sensitivity their emission characteristics should be correlated with the physical morphology and chemical composition of the emitting surface. To this end, we are using the imaging atom probe to correlate the emission characteristics of individual multi-walled nanotubes with their atomic level surface chemical composition and morphology. The initial results of these studies will be presented.