Optical studies of solid C,@ employing time-integrated as well as time-resolved photoluminescence spectroscopy are reported. At low excitation intensity, a richly structured luminescence spectrum is observed. Increasing the excitation intensity leads to pronounced carrier accumulation and to the emission of intense and spectrally broad luminescence. It is concluded that multiple-step absorption processes lead to carrier recombination originating from higher conduction or lower valence band states. and electrically [8] excited, spectrally broad ('white') luminescence have been reported. These optical features of C,, may find important applications, e.g., for second-harmonic light generation, for optical-limiting purposes, and for the realization of white-light emitting electroluminescence diodes.In order to understand the optical properties of the c 6 0 molecule, the character of the chemical bonds between the C atoms has to be considered. The valence electrons of the C atoms undergo a sp2 hybridization, i.e., three electrons of each C atom contribute to the o-bonds, which stabilize the mechanical framework of the soccerball molecule. The remaining p-electron per C atom participates in the formation of n-bonds with orbitals perpendicular to the spherical surface. These delocalized n-states determine the electronic as well as the optical properties of the C 6 , molecule [9, 101. The quantized energy states for the n-electrons are mainly determined by their angular momentum 011 the C,, molecule surface. The energy difference EMo between the highest occupied molecular orbital (HOMO) 11, and the lowest unoccupied molecular orbital (LUMO) t , , amounts to about 1.9eV. However, the corresponding optical transition is dipole forbidden due to the fact that the initial and final wave functions have the same 'ungerade' parity.Solid C,, is normally prepared as a polycrystalline powder, but also large single crystals can be grown [ 111. The C60 molecules occupy the sites of an f.c.c. lattice with a lattice constant of about 14.2 nm. The cohesive energy of the crystal is due to van der Waals interactions between the n-electron systems of the individual c 6 0 units. This intermolecular interaction changes the sharp molecular energy levels of the n-electrons into bands with widths of about 0.5 eV [9, 101. As a consequence, the band gap E, between the 'h,' valence band and the 't,,' conduction band is red-shifted in comparison to the lowest optical transition