Photoion–photoion coincidence study of the fragmentation of the doubly charged N2+2 cation

Formation and fragmentation of the doubly charged N2+2 cation were studied by using the photoion–photoion coincidence (PIPICO) method. Six electronic states of N2+2 were observed. Their ionization energies were measured with uncertainties of about 0.3 eV, which allowed a tentative assignment of these states. It was furthermore demonstrated that N2+2 dissociates into N+(3P)+N+(3P) whichever initial electronic state is populated.