Production of OH⁺(A, ³Π) by He⁺ Impact on H₂O

Helium ion impact on H 2 O exhibits quite a different spectrum from that electron-impact on H 2 O gives. In the former, the OH + A , 3 Π→ X , 3 Σ - band-system can be observed in addition to the OH A , 2 Σ + → X , 2 Π. On the contrary, there is no trace of the OH + bands in the latter. These experimental evidences have been obtained by the crossed-beam technique.