抄録
Helium ion impact on H2O exhibits quite a different spectrum from that electron-impact on H2O gives. In the former, the OH+ A, 3Π→X, 3Σ− band-system can be observed in addition to the OH A, 2Σ+→X, 2Π. 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.