Electron energy-loss spectroscopy (EELS) is used to determine the energies of low-lying singlet and triplet states of the title compound. The EELS measurements give a splitting of 0.45 eV between the two lowest pi --> pi* singlet states, as confirmed by optical absorption measurements, but do not give a discernable splitting between the corresponding triplet states. The experimental results are interpreted with the aid of ab initio electronic structure calculations using the CIS and CASPTZ methods. The calculations are consistent with the experiments, giving a much larger splitting between the pi --> pi* singlet as compared to the pi --> pi* triplet states. They also reveal that the splitting between the two lowest pi --> pi* triplet states is dominated by through-bond (TB) interactions, whereas that between the corresponding singlet states includes also a significant contribution from the dipole-dipole coupling mechanism.