High-resolution infrared and microwave study of 10BF2 OH and 11BF2OH: the 5, 6l, 71, 8l, 91 and 81 91 vibrationally excited states

Abstract

High-resolution (≤2.4×10−3cm−1) Fourier transform infrared spectra of gas-phase 10B-enriched isotopic and natural samples of BF2OH (difluoroboric acid) were recorded in the 400–4000 cm−1 spectral range. Starting from the results of a previous study [Collet, D., Perrin, A., Burger, H., and Flaud, J.-M., 2002, J. Molec. Spectrosc. 212, 118], which involved the v 8 10BF2 out-of-plane bending) and v9 (OH torsion) bands of 11BF2OH, it has been possible to perform the first rovibrational analysis of the v 5 10BF2 bending), v 8 , v 9 and v 8+v 9 bands of’11BF2OH, and of the v 7 (F2BO in-plane bending), v 5, and v 8+v9 bands of 11BF2OH up to very high rotational quantum numbers. In addition, microwave transitions within the 51, 61, 71 and 81 vibrational states of 11BF2OH were measured using predictions from ab initio calculations [Breidung, J., Demaison, J., D'Eu, J.-F., Margules, L., Collet, D., Mkadmi, E. B., Perrtn, A., And Thiel, W., 2004, J. Mol. S ectrosc. (in press)]. The v 5, v 8, v 9 and v 8+v 9 bands of’ bands of 10BF2OH and the v 8+v 9 band of'BF2OH are not significantly affected by ptrturbations, and the experimental 51, 81 and 91 of 10BF2OH and the 8191 energy levels of BF20H and 10BF2OH could be reproduced using a simple Watson-type Hamiltonian. For the v 5 and v 7 bands of 11BF2OH, C-type Coriolis interactions coupling the 51 and 71 energy levels with those of the 72 and 61 dark states, respectively, were accounted for in the calculation. In addition, an updated set of rotational parameters was provided for the unperturbed 81 and 91 vibrational states of 11BF2OH using the data from our previous analysis. In all these cases, the upper state parameters derived in this work enabled the reproduction of both the infrared and microwave data to within experimental uncertainties.