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Using a combination of results from photoemission, electron energy-loss spectroscopy in transmission and gradient-corrected density functional calculations, we have examined the effects of chemical substitution of N for C in the dimerised heterofullerene (C59N)2. We show that there is a new HOMO state, which lies close in energy to the hu-states of C60 and has a significant degree of N-character. In contrast, the lowest lying unoccupied levels have predominantly C-character. The photoemission data of the alkali metal intercalated salts AxC59N reveal signs of at least one additional phase other than the undoped (C59N)2 and an alkali metal saturated phase. At no stage during the intercalation is experimental evidence for metallic behaviour (in the form of a density of states at the Fermi level) observed.

Using a combination of results from photoemission, electron energy-loss spectroscopy in transmission and gradient-corrected density functional calculations, we have examined the effects of chemical substitution of N for C in the dimerised heterofullerene (C59N)2. We show that there is a new HOMO state, which lies close in energy to the hu-states of C60 and has a significant degree of N-character. In contrast, the lowest lying unoccupied levels have predominantly C-character. The photoemission data of the alkali metal intercalated salts AxC59N reveal signs of at least one additional phase other than the undoped (C59N)2 and an alkali metal saturated phase. At no stage during the intercalation is experimental evidence for metallic behaviour (in the form of a density of states at the Fermi level) observed.