ELECTRON-MOMENTUM SPECTROSCOPY OF FULLERENE

The energy-resolved electron-momentum density of fullerene has been me asured. Clear differences are found from the energy-momentum densities of either diamond or graphite. The energy-momentum density of fullere ne can be described as being composed of a sigma band and a split pi b and. The observed spectral momentum densities are compared to the calc ulated orbitals of a C-60 molecule in momentum space. Good agreement i s found. A simple classification of the orbitals is proposed that expl ains elegantly the calculated and observed structures. The splitting o f the pi band can be interpreted as a consequence of the curvature of the carbon network forming the fullerene molecule.