Vertically aligned nanotubes, grown on various substrates by thermal decomposition of a botanical hydrocarbon-camphor, were investigated for field emission application. In a parallel plate (similar to500 gm apart) field emission device, as-grown nanotubes exhibited a turn-on field as low as 2.6 V/mum, whereas the maximum current density observed was 14 mA/cm(2) at an applied field of 7.7 V/mum. Utilizing such an emission efficiency of camphor-grown nanotubes, a model field emission microscope was fabricated with isolated nanotube emitters and informative emission patterns were observed on a fluorescent screen (placed at a working distance of 1-5 cm) at low applied voltages of 300-1000 V. Presence of localized density of states corresponding to pentagonal defects at the emitter tip was identified and discussed. (C) 2003 Elsevier B.V. All rights reserved.