Infrared–vacuum ultraviolet spectroscopy of the CH stretching vibrations of jet‐cooled aromatic azine molecules and the anharmonic analysis

Vibrational spectra of the CH stretching vibration of diazine molecules, pyrimidine and pyrazine, were measured by infrared (IR)–vacuum ultraviolet (VUV) spectroscopy under the jet‐cooled gas‐phase condition. The observed IR spectra were analyzed by three anharmonic algorithms to account for the Fe...

Full description

Saved in:
Bibliographic Details
Published in:Journal of the Chinese Chemical Society (Taipei) 2022-01, Vol.69 (1), p.160-172
Main Authors: Feng, Jun‐Ying, Huang, Qian‐Rui, Nguyen, Ha‐Quyen, Kuo, Jer‐Lai, Ebata, Takayuki
Format: Article
Language:English
Subjects:
Algorithms
Anharmonicity
aromatic azine
Configuration interaction
Coupling (molecular)
CH stretching vibration
Fermi‐resonance
Infrared spectroscopy
IR–VUV spectroscopy
Perturbation theory
Potential energy
Quality assessment
Spectrum analysis
Stretching
supersonic jet
Ultraviolet spectroscopy
Vibration analysis
Vibration measurement
Vibrational spectra
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Vibrational spectra of the CH stretching vibration of diazine molecules, pyrimidine and pyrazine, were measured by infrared (IR)–vacuum ultraviolet (VUV) spectroscopy under the jet‐cooled gas‐phase condition. The observed IR spectra were analyzed by three anharmonic algorithms to account for the Fermi‐resonance (F‐R). The anharmonic analysis of the F‐R pattern was performed with second‐order vibrational perturbation theory (VPT2) with quartic potentials (QPs) at the DFT level of B2PLYP/6–311++G(d,p), followed by vibrational configuration interaction (VCI) method with the same QP. The VPT2 + QP method reasonably reproduced most of the bands in the observed spectra for all the species, especially for pyrimidine, a decent agreement is obtained with respect to the band positions and relative intensities. The analyses of the spectra show that all the observed spectra can be well interpreted by the F‐R between the CH stretching fundamentals and the first overtone and 1 + 1 combination bands involving the in‐plane CH bending vibrations and the contribution of the higher‐order anharmonic coupling to the observed spectra seems to lead to red‐shift of the F‐R patterns. Discrete variable representation based methods with potential energy surfaces at CCSD/aug‐cc‐pVDZ theory with 10 degrees of freedom were also carried out to assess the quality of QP at DFT level. Progress of recent anharmonic calculation enabled to analyze the Fermi‐resonance of the CH stretching vibrations of aromatic molecules
ISSN:0009-4536
2192-6549
DOI:10.1002/jccs.202100366