Reinvestigation of the Fourier transform microwave spectrum of N-ethylacetamide: Pseudo a-type transitions

IF 1.4 4区物理与天体物理 Q4 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Journal of Molecular Spectroscopy Pub Date : 2024-02-01 DOI:10.1016/j.jms.2023.111871

Yoshiyuki Kawashima , Nobuhiko Kuze , Koichi M. T. Yamada , Eizi Hirota

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Abstract

We observed ten pseudo a-type transitions in the E state of N-ethylacetamide (NEAA) using a Fourier transform microwave spectrometer. We found triplets caused by the coupling between the two methyl groups for the observed pseudo a-type transitions. Also, we succeeded in observing similar triplets for the 5 a-type Q-branch transitions, 20 b-type and 7 c-type transitions of the E state of NEAA. These observed triplets allowed us to determinate the potential barrier V₃ to internal rotation of the ethyl-methyl group to be 1078 (12) cm⁻¹. In addition, though the observed intensities of the c-type transitions in the A state were weak, the c-type transition in the E state were observed to be as intense as the b-type transitions of the E state. We explained in this paper the abnormal intensities of the c-type transitions and pseudo a-type transitions in the E state of NEAA.

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重新研究 N-乙基乙酰胺的傅立叶变换微波光谱：伪 a 型跃迁

我们使用傅立叶变换微波光谱仪观测到了 N-乙基乙酰胺（NEAA）E 态的十个伪 a 型跃迁。我们发现，在观测到的伪 a 型跃迁中，两个甲基之间的耦合引起了三连串。此外，我们还成功地观测到了 NEAA E 态的 5 个 a 型 Q 支转变、20 个 b 型转变和 7 个 c 型转变的类似三连串。通过这些观察到的三连串，我们确定了乙基甲基内旋转的势垒 V3 为 1078 (12) cm-1。此外，虽然在 A 态中观察到的 c 型转变强度很弱，但在 E 态中观察到的 c 型转变强度与 E 态的 b 型转变强度相当。我们在本文中解释了东北亚大气中 E 态 c 型转变和伪 a 型转变的异常强度。

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来源期刊

Journal of Molecular Spectroscopy 物理-光谱学

CiteScore

2.70

自引率

21.40%

发文量

审稿时长

29 days

期刊介绍： The Journal of Molecular Spectroscopy presents experimental and theoretical articles on all subjects relevant to molecular spectroscopy and its modern applications. An international medium for the publication of some of the most significant research in the field, the Journal of Molecular Spectroscopy is an invaluable resource for astrophysicists, chemists, physicists, engineers, and others involved in molecular spectroscopy research and practice.