We have measured the total electron detachment cross sections of the negative ions C${}^{-}$, CH${}^{-}$, C${}_2^{-}$, and C${}_2$H${}^{-}$ incident on molecular nitrogen in the velocity range 0.22–0.56 a.u. The data were measured with reliable normalization and, particularly in the critical case of the C${}^{-}$ projectile, the absence of beam contamination due to long-lived metastable states. Comparison of all measurements of cross sections with experimental data for other projectiles shows a common velocity dependence with a maximum near 0.4 a.u. This behavior suggests a connection between the anion-N${}_2$ electron-loss collision dynamics and that of the shape-resonance process dominant in low-velocity electron-N${}_2$ total electron scattering.

• Received 8 March 2013

DOI:https://doi.org/10.1103/PhysRevA.87.062704