Seminars Archive

Exploring the novel electronic properties of molecules- and metals- encapsulated carbon nanotubes

Abstract
Single wall carbon nanotubes (SWCNTs) are now becoming a promising archetype for molecular electronic and spintronic devices in nanoscale. Filling of the SWCNTs with organic molecules opens a new route for tuning the properties of the SWCNTs in a controlled manner, which is important for the practical applications. Besides many successes for the synthesis of molecules- and atoms- encapsulated carbon nanotubes, thorough analysis of the electronic properties of those materials is highly desirable. In this contribution, a detailed study of the filling of the SWCNTs with metallocenes is presented. The metallocenes are organometallic compounds composed of a metal atom sandwiched in-between two or three planer aromatic ligands. Incorporation of the metallocenes inside the SWCNT in bulk scale is observed with photoemission and Raman spectroscopies. Conversion of the filled materials to metal-filled double-wall carbon nanotubes (DWCNT) is successfully performed with heat treatments. Combined investigation of photoemission and resonant Raman spectroscopy on those materials shows evidence for tube-diameter-selective filling of the SWCNT with the metallocenes as well as selected inner-outer tube distances of the DWCNT. From a detailed analysis of the ultra-violet photoemission results, we show the evolution of the degree of charge transfer in those materials. Finally, x-ray Fe 2p photoemission of the metal-filled DWCNT shows a drastic change in spectral shape compared with that of the metallocene-filled SWCNT, reflecting the strong interaction between the metal atoms and SWCNT walls.