State-resolved collision energy dependence of Penning ionization cross sections for N2 and CO2 by He*23S

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Abstract
The state‐resolved collision‐energy dependences of Penning ionization cross sections σ(E) were measured in an energy range (60<E2 and CO2 with He*23S by using a very high‐intensity He* beam (1.8×1015 s−1 sr−1) and detecting energy‐analyzed electrons as functions of time‐of‐flight of He*. The partial ionization cross sections for Π states (N+2B:A2Πu, CO+2B:X2Πg, A2Πu) were observed to increase more rapidly with the increase of the collision energy than those for Σ states (N+2B:X2Σ+g, B2Σ+u, CO+2B:B2Σ+u,C2Σ+g). In the studied energy range, the repulsive walls for end‐on collisions were indicated to be harder than those for side‐on collisions. The directional peculiarity of the potential surfaces was related to the anisotropy in the hybridization of He* orbitals interacting with the target molecules.