Dresden 2003 – scientific programme
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O: Oberflächenphysik
O 12: Postersitzung (Struktur und Dynamik reiner Oberfl
ächen, Grenzfl
äche fest-flüssig, Nanostrukturen, Teilchen und Cluster, Halbleiteroberfl
ächen und Grenzfl
ächen, Zeitaufgelöste Spektroskopie, Rastersondentechniken, Methodisches)
O 12.21: Poster
Monday, March 24, 2003, 18:00–21:00, P1
XPS and STM-Study of Purification Methods for Single-Walled Carbon Nanotubes — •R. Graupner1, A. Vencelová1, L. Ley1, J. Abraham2, and A. Hirsch2 — 1Universität Erlangen, Institut für Technische Physik II, Erwin- Rommelstr. 1, D-91058 Erlangen — 2Universität Erlangen, Institut für Organische Chemie, Henkestr. 42, D-91054 Erlangen
An effective purification technique for single-walled carbon nanotubes (SWCNTs) is a necessary requirement for most application purposes of carbon nanotubes. Different chemical purification techniques to remove amorphous carbon and transition metal impurities were studied by X-ray induced Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy (STM) and Scanning Tunneling Spectroscopy (STS). Our aim is to compare these different recipes with respect to cleanliness, structural defects, and their effect on the electronic properties. XPS allows to monitor atomic compositions, bonding environments, as well as changes in electronic properties caused by a shift in Fermi-level position (doping) for a large ensemble of SWCNTs (Bucky-Paper), whereas STM and STS investigations focus on the structural and electronic properties of single SWCNTs on an atomic scale. It is found that the SWCNTs vary significantly with respect to their structural quality as well as their electronic properties. The effect of these structural alterations on the local electronic properties is investigated by STS. Differences in the Fermi-level position of the SWCNTs are the result of an unintentional doping of the SWCNTs and are caused by the attachment of adsorbates which are introduced in the purification process.