Chiral vector determination of carbon nanotubes by observation...

We have observed clear interference images near the end caps of semiconducting carbon nanotubes with quasiarmchair and zigzag chiral vectors, using a scanning tunneling microscope. We performed a simple tight-binding calculation to simulate the interference patterns, in which Bloch states with k and -k wave vectors were superimposed. The calculations were able to reproduce the observed interference patterns. In addition, we demonstrated that the interference patterns can be categorized by the positions of k_{min} in the Brillouin zone that yield minimum energy in the conduction band, and can give information on the chiral vector of a carbon nanotube.