Charge transfer in intercalated carbon nanostructures

Research project P 14146 Charge transfer in intercalated carbon nanostructures Thomas PICHLER 06.03.2000 The research project deals with the intercalation properties of carbon nanostructures in the form of heterofullerenes, endohedral and carbon nanotubes. One of the central problems in this research field is the interplay between charge transfer and covalent interaction between the intercalated donor or acceptor atoms and the carbon nanostructure. The carbon nanostructures can be doped in three different ways: by intercalation of metal ions, by substitution of carbon atoms with heteroatoms (heterofullerenes) and by encapsulating metal ions (endohedral fullerenes). Up to now only the intercalation properties of pristine fullerenes have been studied in great detail. Raman and infrared (IR) spectroscopy have shown to be excellent tool to analyze the structural, electronic and vibronic properties of these compounds. Metallic, and superconducing, as well as dimeric and polimeric phrases have been observed. However it remains an open question why so few of the doped fullerenes are metallic. To analyze this question and to check on the interplay between charge transfer and covalency a detailed study of the intercalation chemistry of the doped fullerenes will be performed by using Raman, IR and optical spectroscopy. This will allow to figure out the effect of a combination of the different kinds of doping on the electronic and the vibronic properties in these carbon nanostructures. In addition the temperature dependent optical conductivity of the droped intercalated carbon nanotubes. For the intercalated carbon nanotubes the effect of intertube interaction between the individual tubes on charge transfer reaction will be studied in detail by Raman spectroscopy. For the metallic phases Raman and IR spectroscopy will be also applied to get insight in the electron phonon interaction and in the nature of the charge carries in these intercalation compounds.