Figure 1

(a) Kinetic-energy distribution of ${\mathrm{O}}^{-}$ ions arising from DEA to CO at 10.5 eV incident electron energy. The vertical dashed lines in the graph show the regions for processes I and II. The angular distribution (normalized at ${90}^{\circ }$) at above electron energy with ion kinetic energy in the range (b) 0.10–0.65 eV (Process I), and (c) 0.00–0.10 eV (Process II), respectively. The solid curves in (b) and (c) are angular distribution data fitted with the theoretical model using $\Sigma$ + $\Pi$ and $\Sigma$ final-state transition, respectively, under axial recoil approximation.