Electron Emission Sites on Carbon Nanotubes and the Energy Spectra

Abstract
Two kinds of electron emission sites on carbon nanotubes have been clarified; one is a nanoprotrusion exhibiting deformed honeycomb structures composed of carbon hexagons,pentagons and possibly heptagons. The other is either an edged species or adsorbates. The emission spectra show two characteristic features; a broad main peak as compared with theoretical curves based on Fowler-Nordheim theory, and an additional shoulder at about 0.5 eV from E F, of which the features are observed independent of the emission direction. The broad main peak may indicate that energy band bending occurs near the emission sites.