Electron impact dissociation and ionization of N+2

Absolute cross sections for electron impact ionization, dissociative excitation (DE) and dissociative ionization of N-2(+) ions are measured in the energy range from threshold to 2500 eV. The animated crossed electron-ion beam method has been employed. The individual contributions of ionization products (N-2(2+)) and dissociation fragments (N+), which have both identical mass-to-charge ratio and average velocity, are deduced from the analysis of product velocity distributions. Particular attention was paid to determining the transmission efficiency for dissociation fragments, since their collection was incomplete during the measurements. Threshold energies and kinetic energy released to dissociation fragments are measured. The role of states contributing to different reactions is discussed. For DE, the present results are found to be much smaller than the results of Peterson et al (1998). For ionization (single and dissociative), a satisfactory agreement with their result is obtained as well as with the prediction of Kim et al (2000) obtained in the binary-encounter Bethe approximation.