Abstract Submitted to the    NANOTUBE'04 Conference:

The local structure of intercalated single-walled carbon nanotubes with rubidium ions (Rb-SWNT) produced by electric charge technique and doped in vapour phase has been studied by Rb K-edge extended x-ray-absorption fine structure (EXAFS). The EXAFS spectra have shown the sensitivity of the local arrangement of alkali ions in SWNT. The first coordination shell of Rb ions corresponding to the first carbon neighbours have a clear time doping dependence. The superstructure of alkali is found to be incommensurate with the graphitic layer of the tubes for low time of doping. By contrast, for samples doped at saturation, the superstructure of alkali is found to be commensurate with the graphitic layer and disordered. Comparison between ab initio simulations of EXAFS spectra and experimental data indicates that Rb ions are mainly located inside the tubes and around the bundles. Theses results are in agreement with X-ray and neutron diffraction experiments performed on the same samples. These results question the interstitial site as the preferential absorption site.