Fermi electron wave packet interference images on carbon nanotubes at roomtemperature

We report on the structure and electronic properties of single wall carbon nanotubes tips with atomically spatial resolution. Scanning tunneling micro scopy shows topographic images of closed tips with a variety of geometrical structure; these include round, conical, as well as tips with a messy shap e. Standing wave pattern of the charge density is observed at the tube cap which is formed due to constructive interference between the electronic sta tes and its reflection on the nanotube tips. Atomically resolved images sho w asymmetry in the charge density that decay out within 6 nm away from the cap. These distinctive tip states do not exist elsewhere on the tube and ar e related to the presence of topological defects at tube ends. (C) 2001 Ame rican Institute of Physics.