The 2 ν1, 2 ν2 and 2 ν3 overtones of FClO 3

Abstract

The infrared spectra of the 2 ν 1, 2 ν 2 and 2 ν 3 overtones of perchloryl fluoride, FClO 3, have been recorded at high resolution using monoisotopic pure samples. Four symmetric top species have been investigated: F 35Cl 16O 3, F 37Cl 16O 3, F 35Cl 18O 3 and F 37Cl 18O 3. The v i = 2, i = 1, 2, 3 vibrationally excited states are totally symmetric, so these overtones correspond to parallel bands of medium/weak intensity, centered from 2010 to 2120 cm −1 (2 ν 1), from 1390 to 1430 cm −1 (2 ν 2) and from 1070 to 1100 cm −1 (2 ν 3). Most of the bands are unperturbed and their analysis was straightforward. The band origins, the rotational and centrifugal molecular constants in the v 1 = 2, v 2 = 2 and v 3 = 2 states have been determined, with standard deviations of the fits from 0.00024 to 0.00067 cm −1. The 2 ν 1 overtones of F 35Cl 16O 3 and F 37Cl 16O 3 are perturbed by an A 1/ E Coriolis resonance between the v 1 = 2 state and one E component of the v 4 = 1, v 6 = 2 manifold. The 2 ν 2 of F 37Cl 18O 3 is perturbed by the same kind of interaction involving the v 1 = v 6 = 1 ( E) state, at about 1396 cm −1. In these bands the resonance is localized on rotational levels with specific J and K values. As a consequence, a few transitions of the perpendicular bands involving the interacting levels could be identified in the spectra. A simultaneous fit of the transitions assigned to the dyads has been performed and the parameters of the excited states have been determined, including the high order Coriolis interaction coefficient C 11 1 . The anharmonic constants x 11, x 22, x 33 of all the studied isotopologues of FClO 3, x 46 of F 35Cl 16O 3, x 46 + g 46 of F 37Cl 16O 3 and x 16 of F 37Cl 18O 3, have been derived.