Microwave electronic spectroscopy, electric field dissociation and photofragmentation of the H2 + ion

Three Microwave electronic transitions in the H+2 molecular ion have been observed between the 1sσg ground state and the long-range minimum of the first excited 2pσu state. Electric field dissociation is used as an indirect method for detecting the transitions. Calculations of electric field dissociation are presented in which the rotation of the molecule is included, allowing predictions of the strengths of the electric field required to dissociate particular vibration–rotation levels in the 1sσg state. The 2pσu(v= 0, N= 2)–1sσg(v= 19, N= 1) transition was also observed using microwave photodissociation and calculations of the photodissociation cross-sections are given. An unexpected splitting was observed in two of the transitions and is interpreted in terms of g/u symmetry breaking caused by the proton Fermi contact interaction.