High-resolution infrared and microwave study of 10 BF 2 OH and 11 BF 2 OH: the 5 1 , 6 1 , 7 1 , 8 1 , 9 1 and 8 1 9 1 vibrationally excited states

Author： Perrin A. Carvajal-Zaera M. Dutkiewicz Z. Flaud J.-M. Collet D. Bürger H. Demaison J. Willaert F. Mäder H. Larsen N. W.

Publisher： Taylor & Francis Ltd

ISSN： 1362-3028

Source： Molecular Physics, Vol.102, Iss.14-15, 2004-07, pp. : 1641-1652

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Abstract

High-resolution (≤2.4×10 −3 cm −1 ) Fourier transform infrared spectra of gas-phase 10 B-enriched isotopic and natural samples of BF 2 OH (difluoroboric acid) were recorded in the 400-4000 cm −1 spectral range. Starting from the results of a previous study [C OLLET , D., P ERRIN , A., B ÜRGER , H., and F LAUD , J.-M., 2002, J. Molec. Spectrosc . 212 , 118], which involved the &ngr; 8 (BF 2 out-of-plane bending) and &ngr; 9 (OH torsion) bands of 11 BF 2 OH, it has been possible to perform the first rovibrational analysis of the &ngr; 5 (BF 2 bending), &ngr; 8 , &ngr; 9 and &ngr; 8 + &ngr; 9 bands of 10 BF 2 OH, and of the &ngr; 7 (F 2 BO in-plane bending), &ngr; 5 , and &ngr; 8 + &ngr; 9 bands of 11 BF 2 OH up to very high rotational quantum numbers. In addition, microwave transitions within the 5 1 , 6 1 , 7 1 and 8 1 vibrational states of 11 BF 2 OH were measured using predictions from ab initio calculations [B REIDUNG , J., D EMAISON , J., D'E U , J.-F., M ARGULÈS , L., C OLLET , D., M KADMI , E. B., P ERRIN , A., and T HIEL , W., 2004, J. Mol. Spectrosc . (in press)]. The &ngr; 5 , &ngr; 8 , &ngr; 9 and &ngr; 8 + &ngr; 9 bands of 10 BF 2 OH and the &ngr; 8 + &ngr; 9 band of 11 BF 2 OH are not significantly affected by perturbations, and the experimental 5 1 , 8 1 and 9 1 of 10 BF 2 OH and the 8 1 9 1 energy levels of 10 BF 2 OH and 11 BF 2 OH could be reproduced using a simple Watson-type Hamiltonian. For the &ngr; 5 and &ngr; 7 bands of 11 BF 2 OH, C-type Coriolis interactions coupling the 5 1 and 7 1 energy levels with those of the 7 2 and 6 1 dark states, respectively, were accounted for in the calculation. In addition, an updated set of rotational parameters was provided for the unperturbed 8 1 and 9 1 vibrational states of 11 BF 2 OH 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.