The rotational spectra, isotopically independent parameters, and interatomic potentials for the X1 2Π3/2 and X2 2Π1/2 states of BrO

Observations of the rotational spectrum of BrO have been extended to include vibrational levels up to v = 8 in the X-1 (2)Pi (3/2) and v = 7 in the X-2 (2)Pi (1/2) states. The rotational spectra of isotopically enriched (BrO)-O-18, X-1, v = 0, 1 and X-2, v = 0 have been observed as well. The spectra of all four isotopic species have been fit to a Hamiltonian in which the parameters have fixed isotopic ratios. An extensive set of isotopically independent parameters has been determined. Interatomic potentials have been derived for both the X-1 and X-2 states. The hyperfine constants and their vibrational dependencies have been determined more precisely and several of them have been determined for the first time. These are interpreted in terms of the electronic structure of the molecule. The isotope relations among the constants have provided a means of decorrelating the electron spin-rotation constant gamma from the fine-structure centrifugal distortion constant, A(D), and have allowed the first determination of an effective value for gamma. (C) 2001 Academic Press.