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The manufacture of a liquid metal ion source based on carbon nanotubes is described. Multi-wall carbon nanotubes were attached to the tip of a tungsten needle forming a fibre which was subsequently coated with a layer of indium. The onset of ion emission was observed at about 850 V, a value much lower than that for a conventional indium needle emitter. However, the nanotube fibres degrade rapidly at higher voltages and eventually disappear from the needle. [ABSTRACT FROM AUTHOR]

The dielectrophoretic attachment of multi-wall carbon nanotubes (MWNTs) on the apex of tungsten needles immersed in a suspension was investigated. Growth of branched nanotube fibrils out of the needle surface was observed when an ac bias with a frequency of 1 MHz was applied. The fibrils finally coagulate to a single nanotube fibre anchored at the tip's apex during a retraction of the tip from the suspension. Because of the very high dielectric constant of MWNTs, a moderate electric field intensity is sufficient for attaching nanotubes on the tip. The former was approximately two orders of magnitude lower than that reported in previous experiments. The diameter of the nanotube fibres can be controlled by the applied voltage. [ABSTRACT FROM AUTHOR]