The 2ν5 overtone bands of perchloryl fluoride

The high-resolution infrared spectra of the monoisotopic species F35Cl16O3, F37Cl16O3, F35Cl18O3 and F37Cl18O3 have been studied in the region of the 2ν5 overtones, from 1100 to 1200 cm−1. Both the parallel 2ν50 and the perpendicular 2ν5∓2 components are clearly observed in the spectra, their origins differing by about 0.4 cm−1. In each spectrum about 2000 transitions have been assigned, 35% of them belonging to 2ν50. The parallel and perpendicular bands in each manifold have been analyzed separately since no evidence of perturbations has been observed. The rovibration parameters of the v5 = 2, l5 = 0 and v5 = 2, l5=∓2 excited states have been obtained. For the four species combining the 2ν50 and 2ν5∓2 band origins with those of the ν5 fundamentals the harmonic wavenumbers, ω50, and the x55 and g55 anharmonicity constants have also been derived.