The dielectric response of the H_2Ti_3o_7 nanotube investigated by valence electron energy loss spectroscopy

摘要

The dielectric response of an anisotropic nanostructure, individual H_2Ti_3O_7 nanotube with ～8-10 nm diameter, has been investigated using both momentum transfer dependent and spatially resolved valence electron energy loss spectroscopies. The dielectric response of an individual nanotube is found to be dominated by several surface related excitations and defect states, although its basic electronic structure (such as the band gap and single electron interband transitions) is similar to that of TiO_2. The possible origins of the surface excitations in such a tubular structure are also discussed.