Diabatic-basis potential-energy curves of N₂ excited states relevant to ultraviolet photoabsorption and photodissociation. The energy scale is referenced to v = 0, J = 0 of the ground state and is related to the wavelength scale assuming transitions from this fundamental level. Also indicated are the excitation states of atomic products arising from dissociation and the absorption limit imposed by the ionisation of atomic H. The potential-energy curves of the and states are indistinguishable at the plotted scale. The N₂ ionisation potential energy occurs at 15.4 eV in this figure.