Ultraviolet photoelectron spectra of C 76 and K xC 76

Abstract

Ultraviolet photoelectron spectra of C 76, one of the fullerene family of compounds, have been measured with a synchroton radiation light source. The photoemission spectral onset is 1.3 eV below the Fermi level, which is equal to that of C 84 but is about 0.5 eV smaller than that of C 60 or C 70. The relative intensity of the photoemission spectral features is independent of the incident photon energy change. Photoemission spectral changes for C 76 during potassium dosing are also measured. A new band becomes distinct between the Fermi level and the HOMO band, when the potassium content ( x in K x C 76) is equal to or greater than 1.1. The spectral onset moves toward the Fermi level with increasing potassium dosage, approaching it but never crossing it. This indicates that potassium-dosed C 76 could be a narrow gap semiconductor.