Microwave electronic spectrum of the H2+ ion

Abstract We report the observation of a microwave transition in the H 2 + ion, arising from an electronic transition between the highest bound vibration-rotation level of the 1 sσ g ground state, with v = 19, N = 1, and the v = 0, N = 2 level of the 2pσ u long-range van der Waals state.