SCANNING PROBE MICROSCOPY OF CARBON NANOTUBES

Multi-wall carbon nanotubes (MWNTs) deposited on various substrates we re analysed by scanning tunneling microscopy (STM) and atomic force mi croscopy (AFM). A dispersion of carbon nanotubes in ethanol was drawn through a 200 nm pore ceramic filter to produce a thin film of nanotub es. This film was brushed along one direction with a Teflon rod involv ing a change of optical properties. Scanning probe images document tha t brushing alters the orientation of carbon nanotubes from random to a ligned within the plane. To characterize individual nanotubes, a dropl et of nanotubes and nanoparticles suspension (solvent ethanol or chlor oform) was applied to highly oriented pyrolytic graphite (HOPG) as wel l as to a polycrystalline gold film, and allowed to evaporate. This yi elded a random distribution of nanotubes on the substrate. Individual nanotubes as well as aggregates of nanotubes could be Identified and c haracterized by STM and AFM on both HOPG and polycrystalline gold subs trates. AFM measurements suggest that carbon nanotubes adhere more tig htly to the gold substrate due to the higher surface roughness. The we ak binding allows us to move carbon nanotubes on a graphite surface at much lower force loads than on polycrystalline gold films. STM imagin g of nanotubes on polycrystalline gold films yielded atomic resolution . (C) 1998 Elsevier Science Ltd. All rights reserved.