High-Resolution Analysis of the ν1 + 2ν2, 2ν2 + ν3, 2ν1, ν1 + ν3, and 2ν3 Bands of H280Se

Abstract

High-resolution Fourier transform spectra of monoisotopic H280Se have been recorded with a resolution of 7 × 10−3 cm−1 in the 4210-4850 cm−1 spectral range. Their rovibrational analysis led to an extensive and precise set of rotational levels for the (1 2 0), (0 2 1), (2 0 0), (1 0 1), and (0 0 2) vibrational states of this molecule. To fit these levels satisfactorily it proved necessary to take explicitly into account in the Hamiltonian not only the strong Coriolis and Darling-Dennison interactions coupling the rotational levels of the {(2 0 0), (1 0 1), (0 0 2)} vibrational states and the strong Coriolis interaction coupling the levels of (1 2 0), (0 2 1)}, but also weak interactions linking the rotational levels of these two groups of vibrational states; indeed for J values around 15 and above, there appear crossings between the levels despite the differences in the bandcenters. In this way, all the experimental levels were satisfactorily calculated and a precise set of vibrational energies and rotational and coupling constants was obtained for the five vibrational states (1 2 0), (0 2 1), (2 0 0), (1 0 1), and (0 0 2) of H280Se with the following bandcenters: ν0 (ν1 + 2ν2) = 4370.60800 cm−1, ν0 (2ν2 + ν3) = 4377.61844 cm−1, ν0 (2ν1) = 4615.32816 cm−1, ν0 (ν1 + ν3) = 4617.39318 cm−1, and ν0 (2ν3) = 4702.54744 cm−1.