Kinetic-energy release in N2 fragmentation by charge-changing collisions of 2-MeV C+ ions

Collision-induced fragmentation of N₂ was investigated for 2-MeV C⁺ ions under charge-changing conditions of C⁺→C^q+ (q=0,2,3). Coincidence measurement of fragment ions was performed by means of a momentum three-dimensional imaging technique at scattering angles of θ=0 and 1.0 mrad. Kinetic-energy release (KER) obtained for a fragmentation channel of N₂²⁺→N⁺+N⁺ was found to differ significantly in electron loss and capture collisions. In two-electron-loss collisions (C⁺→C³⁺), KER spectra were essentially identical for θ=0 and 1.0 mrad. It is concluded that the energy level of dissociating excited states of N₂²⁺ may be saturated when the interaction strength, defined as (q)/(vb), exceeds 0.65, where q and v are the charge and the velocity, respectively, of an incident ion, and b is the impact parameter.