Field emission of individual carbon nanotube with <i>in situ</i> tip image and real work function

The field emission properties of individual multiwalled carbon nanotubes have been measured simultaneously in correlation to the emitter images and their real work functions at tips by the in situ transmission electron microscopy method. The field emission of a single nanotube still follows the Fowler-Nordheim law. The field enhancement factor has been determined by the real work function rather than a given constant. In situ imaging and measurement show that the work function at the nanotube tip depends strongly on its structure and surface condition. This study provides an approach of direct linking field emission with the in situ emitter structure and the real work function at the emitter tip.