2011ApJ...729L...2F

Five pure rotational transitions of H₂F⁺ generated by a discharge in an HF/H₂/Ar mixture were observed in the range 473-774 GHz with a backward-wave oscillator based submillimeter-wave spectrometer. A simultaneous analysis of the rotational lines with 120 combination differences for the ground state derived from the infrared spectra was carried out to determine the precise molecular constants for the ground state. The rotational transition frequencies that lie below 2 THz were calculated, together with their estimated uncertainties, to facilitate future astronomical identifications. The chemistry for H₂F⁺ formation in interstellar space is discussed in comparison with a case for recently detected H₂Cl⁺.