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Building blocks of the future

December 05, 2002

Structure and properties of carbon nanostructures

The discovery in 1985 of fullerenes, tiny carbon balls of nanometer dimensions, ushered in a new era in international science. Only a few years later (1991) scientific interest also started to focus on so-called carbon nanotubes. The discovery of improved production methods (1996) has meanwhile turned the analysis of the structure and properties of nanotubes into a vigorously growing field of research.

These molecules, measuring about one-thousandth of the diameter of a human hair, have the potential to become the building blocks of future information and energy technologies. Sponsored by the Austrian Science Fund (FWF), Thomas Pichler has put carbon nanotubes at the centre of his research interest at the Institute of Materials Physics at the University of Vienna. Through his work, he has made a considerable contribution to the basic understanding of the electronic structure of these molecules and has recently received the Fritz-Kohlrausch Award of the Austrian Physical Society for his achievements in this field.

Transistors consisting of one single molecule, flat screens, molecular gears and storage units, bearings and telescopic springs - all could be produced on the basis of carbon nanostructures in the foreseeable future. They are extremely resistant to tension and shear, are highly flexible and can exhibit insulating, semiconducting, metallic or even superconducting properties. In short, they are the ideal building blocks for molecular nanoelectronics.

Detailed knowledge of ideal production methods, structure, properties and functionalities is therefore the key to a technology of a completely new quality. "Based on optical spectroscopy and in comparison with high-energy spectroscopy measurements (carried out at the IFW Dresden), we have used model structures of fullerenes and carbon nanotubes to show how the electronic structure and optical properties of these nanostructures depend on their size, their local molecular structure and their conductivity", explains Pichler. The electronic structure of the nanomolecules, for instance, is determined by graphite down to a particle size of 4 nanometers; the molecular electron structure has an effect only in smaller particles.

Pinpoint structural changes
Pichler was interested not only in analysing the properties but also in modifying the electronic and structural properties of the carbon nanostructures in a targeted way. "We also put major emphasis on the type and dynamics of the charged particles of the nanostructures. We succeeded in filling fullerenes and nanotubes with metal ions and investigating the charge transfer and the mutual interactions between the fullerene cage and the metal ions. Our results are key values for further research on carbon nanostructures", explains Pichler. Further projects, some of them in cooperation with industry, are in the pipeline, such as the production of functionalised nanotubes and the investigation of the interior of filled nanotubes.

FWF Der Wissenschaftsfonds