Electronic properties of low-dimensional carbon clusters

The field emission of linear carbon chains is studied by ab initio calculations of their ground state properties and employing the WKB approximation for determining the emission current in an applied constant electric field. It is found that the valence electrons are able to screen the external electric field very efficiently suggesting a metallic behavior. For fields of the order of 0.6 V/A, a chain consisting of 10 carbon atoms can yield currents as large as a μA, the latter being produced by electrons coming mostly from the highest occupied energy level. Thus, such an ‘electron gun’ is expected to be highly monoenergetic.