IOP Publishing, Journal of Physics: Condensed Matter, 43(19), p. 436223, 2007
DOI: 10.1088/0953-8984/19/43/436223
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We have measured the angle-resolved photoemission spectroscopy of a C60 single crystal in the low photon energy region from 13.0 to 34.0 eV with small increments (0.5 or 1.0 eV). The ratios of partial photoionization cross-sections for the HOMO and HOMO-1 bands exhibit many fine structures. The energy positions of the fine structures agree well with the giant resonances of dipole transition between individual molecular orbitals, which were predicted by a quantum chemistry model. The magnitudes of the HOMO/HOMO-1 ratios, however, indicate further theoretical works are still needed. The important role of collective excitation in the photoionization cross-section of C60 is suggested.