title: Isotope engineering of carbon nanotube systems.
abstract: The synthesis of a unique isotope engineered system, double-wall carbon nanotubes with natural carbon outer and highly 13C enriched inner walls, is reported from isotope enriched fullerenes encapsulated in single-wall carbon nanotubes (SWCNTs). The material allows the observation of the D line of the highly defect-free inner tubes that can be related to a curvature induced enhancement of the electron-phonon coupling. Ab initio calculations explain the inhomogeneous broadening of inner tube Raman modes due to the distribution of different isotopes. Nuclear magnetic resonance shows a significant contrast of the isotope enriched inner SWCNTs compared to other carbon phases and provides a macroscopic measure of the inner tube mass content. The high curvature of the small diameter inner tubes manifests in an increased distribution of the chemical shift tensor components.
authors.affiliation: Institut für Materialphysik, Universität Wien, Strudlhofgasse 4, A-1090 Wien, Austria.
authors.forename: F
authors.initials: F
authors.lastname: Simon
authors.forename: Ch
authors.initials: Ch
authors.lastname: Kramberger
authors.forename: R
authors.initials: R
authors.lastname: Pfeiffer
authors.forename: H
authors.initials: H
authors.lastname: Kuzmany
authors.forename: V
authors.initials: V
authors.lastname: Zólyomi
authors.forename: J
authors.initials: J
authors.lastname: Kürti
authors.forename: P M
authors.initials: PM
authors.lastname: Singer
authors.forename: H
authors.initials: H
authors.lastname: Alloul