title: Effects of gas adsorption and collisions on electrical transport in single-walled carbon nanotubes
abstract: Degassing of bundles of single-walled carbon nanotubes in vacuum at 500 K is found to drive the thermoelectricpower (TEP) strongly negative, indicating that the degassed metallic tubes in a bundle are n type. The magnitude of the negative TEP indicates that important asymmetry in the electronic carbon pi bands exists near the Fermi energy. Easily measurable increases in the TEP ( approximately 5-10 &mgr;V/K) and resistivity ( 2%-10%) are observed at 500 K upon exposure to N2 and He, suggesting that even gas collisions with the nanotube wall can contribute significantly to the transport properties.
authors.affiliation: Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.initials: GU
authors.lastname: Sumanasekera
authors.initials: CK
authors.lastname: Adu
authors.initials: S
authors.lastname: Fang
authors.initials: PC
authors.lastname: Eklund