MICROWAVE ELECTRONIC-SPECTRA OF THE AR-2(-2(+) IONS - A COMBINED NEUTRAL ION-MOLECULAR BEAM TECHNIQUE() AND NE)

We describe a new ion source in which a nozzle beam of neutral molecul es is ionised by an electron beam and the resulting molecular ion beam is studied by microwave spectroscopic methods. This ionisation techni que results in significant population of the near-dissociation levels of the molecular ion, so that a sensitive state-selective electric fie ld dissociation method can be used to detect the spectra. We have obse rved the first state-to-state resonant electronic spectra of the Ar-2( +) and Ne-2(+) ions.