Abstract We have recorded the infrared absorption spectrum of pyrrole at 0.005 cm −1 spectral resolution using a Fourier transform interferometer. The rotational analysis of the symmetric out-of-plane C–H bend 22 1 0 fundamental band at 722.132993(5) cm −1 was performed, allowing 6760 lines to be assigned. These lines were fitted simultaneously to literature data on ν 1 [A. Mellouki, R. Georges, M. Herman, D. L. Snavely, and S. Leytner, Chem. Phys. 220, 311–322 (1997)] and microwave lines [G. Wlodarczak, L. Martinache, J. Demaison, and B. P. Van Eijck, J. Mol. Spectrosc. 127, 200–208 (1988)]. A set of rotation parameters was determined for the ground state in I r and III r representations, together with vibration–rotation constants for the v 1 = 1 and v 22 = 1 vibrational states. The fine structure in the strongest of the hot bands in that range was highlighted by division, from the experimental data, of the spectrum of the 22 1 0 band, computed using the vibration–rotation parameters. The rotational assignment of 930 lines in the strongest hot band was performed. The 22 1 0 24 1 1 vibrational assignment is proposed, leading to x 22,24 = 1.90 cm −1 . The transition dipole matrix element for the 22 1 0 band is estimated to ‖〈Ψ 22 ‖μ c ‖Ψ 0 〉‖ = 2 × 10 −4 D.

中文翻译：

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吡咯 (12C4H5N) 中 ν1、ν22、ν24、ν22+ ν24 和基态的旋转振动常数

摘要 我们使用傅里叶变换干涉仪记录了吡咯在 0.005 cm -1 光谱分辨率下的红外吸收光谱。对 722.132993(5) cm -1 处的对称面外 C-H 弯曲 22 1 0 基带进行旋转分析，允许分配 6760 条线。这些线同时拟合到 ν 1 [A. Mellouki、R. Georges、M. Herman、DL Snavely 和 S. Leytner，化学。物理。220, 311–322 (1997)] 和微波线路 [G. Wlodarczak、L. Martinache、J. Demaison 和 BP Van Eijck、J. Mol。光谱c。127, 200–208 (1988)]。为 I r 和 III r 表示中的基态确定了一组旋转参数，以及 v 1 = 1 和 v 22 = 1 振动状态的振动-旋转常数。通过使用振动-旋转参数计算的 22 1 0 波段的光谱，从实验数据中划分出该范围内最强热波段的精细结构。执行了最强热带中 930 条线的轮换分配。提出了 22 1 0 24 1 1 振动分配，导致 x 22,24 = 1.90 cm -1 。22 1 0 波段的跃迁偶极矩阵元素估计为 ‖〈Ψ 22 ‖μ c ‖Ψ 0 〉‖ = 2 × 10 -4 D。