Fragmentation dynamics of diatomic molecules under proton impact: Kinetic energy release spectra of CO ^q+ and NO ^q+ ( q = 2, 3) molecular ions

We report the fragmentation dynamics of triply charged, diatomic, molecular ions of NO and CO. Dissociative fragmentation after multiple ionization of NO and CO is studied under the impact of 200 keV proton beam using a recoil-ion momentum spectrometer. Kinetic Energy Release distributions (KERDs) for various fragmentation channels were obtained. We have also calculated the potential energy curves (PECs) for ground and several excited states of NO ^3+ and CO ^3+ molecular ions using the multi-reference configuration interaction (MRCI) method. The obtained KERDs are discussed in the background of the calculated PECs as well as the simple Coulomb excitation model. Coulomb breakup of the unstable precursor molecular ion shows a clear preference for the N ^2+ + O ^+ (and C ^2+ + O ^+ ) fragmentation channel. Graphic abstract