Theoretical study of field emission by a four atoms nanotip: implications for carbon nanotubes observation

A fully three-dimensional quantum model is developed to simulate the emission of electrons by a nanotip in applied fields ranging from 0.4 to 0.8 V/A and their diffusion by an extended molecule. It is shown that the widening of the beam, when the applied field is increased, can be attributed to an increase in the number of emitting atoms. Simulated images of a (9,0) carbon nanotube, in a Fresnel projection microscope-type setup, for various applied fields, reproduce the experimental, so-called, "sucking-in" effect. The relationship between this effect and the transmission probability of the nanotube is studied.