Vibrational and electronic excitations of (C59N)2

High-resolution electron energy loss spectroscopy (HREELS) has been used to investigate the vibrational and electronic excitations of the modified fullerene C59N in the form of a multilayer film deposited on single crystal graphite C(0001). The vibrational modes show a strong relation to those of C60, except for two new modes resulting from the dimerisation: an intermolecular mode around 17 meV and a dipole-active mode at 104 meV. The electronic excitation spectrum is — regarding the interband transitions — also similar to that of C60, despite a broadening due to the lower symmetry in (C59N)2. However, the first excitonic excitations at 1.58 and 1.73 eV are dipole-allowed in the heterofullerene, in stark contrast to the situation in C60.