Absolute infrared vibrational band intensities of molecular ions determined by direct laser absorption spectroscopy in fast ion beams

The technique of direct laser absorption spectroscopy in fast ion beams has been employed for the determination of absolute integrated band intensities (S0v) for the ν3 fundamental bands of H3O+ and NH+4. In addition, the absolute band intensities for the ν1 fundamental bands of HN+2 and HCO+ have been remeasured. The values obtained in units of cm−2 atm−1 at STP are 1880(290) and 580(90) for the ν1 fundamentals of HN+2 and HCO+, respectively; and 4000(800) and 1220(190) for the ν3 fundamentals of H3O+ and NH+4, respectively. Comparisons with ab initio results are presented.