Dennis Lichtenberger (University of Arizona, Tucson): "Prior to this work, the intriguing truncated icosahedral 'soccer ball' structure of the C60 molecule had been surmised from detection of microscopic amounts of the molecule and from numerous theoretical calculations of the electronic structure and bonding.
"Following the synthesis of milligram quantities of C60 at the University of Arizona by Donald Huffman, we set out to measure its full valence and core ionization spectrum. The ionizations provide the most direct experimental probe of the electronic structure of a molecule.
"The-first significant observation was that, although the 60 carbon atoms provide 60 electrons to the valence pi ionization bands, only a few ionizations were observed in the valence energy region. This is a consequence of the high symmetry of the molecule, which, unlike any other molecule at the time, allowed for four-fold and five-fold degenerate electron energy levels. The first two separate...