Abstract Rotationally-resolved infrared absorption spectra of the two lowest-energy fundamental bands for each of the three infrared active symmetry species of 2,5-norbornadiene (C2v point group symmetry; asymmetry parameter κ = −0.2203), ν11 (a1), ν12(a1), ν28(b1), ν29(b1), ν38(b2), and ν39(b2), have been measured, assigned and fit to a semi-rigid rotor Hamiltonian to produce a set of spectroscopic constants for each band. The fit band centers are ν11 (a1), c-type transitions, 728.852357(3) cm−1; ν12 (a1), c-type transitions, 417.31604(1) cm−1; ν28 (b1), a-type transitions, 656.719741(3) cm−1; ν29 (b1), a-type transitions, 500.31425(1) cm−1; ν38 (b2), b-type transitions, 800.82243(2) cm−1; and ν39 (b2), b-type transitions, 539.23110(6) cm−1. Using ground state combination differences from the ν11 and ν28 bands and previously published microwave data, an improved set of ground state spectroscopic constants was fit for the parent isotopologue of the molecule.

中文翻译：

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2,5-降冰片二烯在 400 和 850 cm-1 之间的旋转振动光谱

摘要 2,5-降冰片二烯（C2v 点群对称性；不对称参数 κ = -0.2203）、ν11 (a1)、ν12 的三种红外活性对称物质中的每一种的两个最低能量基带的旋转分辨红外吸收光谱(a1)、ν28(b1)、ν29(b1)、ν38(b2) 和 ν39(b2) 已被测量、分配并拟合到半刚性转子哈密顿量，从而为每个波段产生一组光谱常数。拟合带中心为 ν11 (a1)，c 型过渡，728.852357(3) cm-1；ν12 (a1)，c 型跃迁，417.31604(1) cm−1；ν28 (b1)，a 型跃迁，656.719741(3) cm−1；ν29 (b1)，a 型跃迁，500.31425(1) cm−1；ν38 (b2)，b 型跃迁，800.82243(2) cm−1；和 ν39 (b2)，b 型跃迁，539.23110(6) cm-1。