Electronic structure at carbon nanotube tips

We discuss a number of recent observations on carbon nanotubes tips. Eviden ce from scanning tunneling microscopy (STM) and spectroscopy (STS) experime nts [1] indicates that the topology of the carbon bond network at the tip, and in particular the relative location of pentagons in the curved regions of the caps, is ultimately responsible for the space-resolved electronic pr operties of the tubes. The theoretical analysis of the local density of (el ectronic) states (LDOS) is shown to be a powerful tool to rationalize the e xperimental data. Images of carbon nanotube tips acquired in field emission microscopy (FEM) experiments [2] can be related to the STM/STS observation s.