{"title":"The 2ν3/ν2/ν5/ν3 + ν6 band system of CH3Br revisited: Anharmonic and Coriolis interactions in a four-level system near 1400 cm−1","authors":"Adina Ceausu–Velcescu , Wilfried Tchana Betnga , Fridolin Kwabia Tchana , Laurent Manceron , Xavier Landsheere","doi":"10.1016/j.jms.2023.111795","DOIUrl":null,"url":null,"abstract":"<div><p><span>The infrared spectrum<span> of gaseous methyl bromide (CH</span></span><sub>3</sub>Br) in natural abundance has been analyzed with high resolution, between 1150 and 1700 cm<sup>−1</sup>. In this spectral region, two fundamental bands, ν<sub>2</sub> (A<sub>1</sub>) and ν<sub>5</sub> (E), an overtone 2ν<sub>3</sub> (A<sub>1</sub>) and a combination band ν<sub>3</sub> + ν<sub>6</sub> (E) occur. The novelty of the present study consists in considering, besides the strong Coriolis and α-interactions coupling the v<sub>2</sub> = 1 and v<sub>5</sub> = 1 levels, a large variety of anharmonic and rovibrational interactions involving also the v<sub>3</sub> = 2 and v<sub>3</sub> = v<sub>6</sub> = 1 levels. For this latter level, the data set belonging to the ν<sub>3</sub> + ν<sub>6</sub> combination band has been extended with respect to previous work of Ouahman <em>et al.</em> [<em>Spectrochim. Acta</em> <strong>45A</strong> (1989) 175–179], to about thousand assigned transitions with <span><math><mrow><mo>-</mo><mn>6</mn><mo>≤</mo><mi>K</mi><mo>·</mo><mi>Δ</mi><mi>K</mi><mo>≤</mo><mo>+</mo><mn>16</mn></mrow></math></span>. Thanks to the completeness of the theoretical model, the global standard deviation of the reproduction of the experimental wavenumbers in the ν<sub>2</sub>/ν<sub>5</sub> system was greatly improved with respect to the previous high-resolution study of Kwabia Tchana et al. [<em>J. Mol. Spectrosc.</em> <strong>228</strong> (2004) 441–452]. For this Coriolis-interacting band system, two different reduction schemes, according to the theory of Stříteská <em>et al.</em> [<em>J. Mol. Spectrosc.</em> <strong>256</strong> (2009) 135–140], were applied and were proved to be equally successful.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"395 ","pages":"Article 111795"},"PeriodicalIF":1.4000,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Molecular Spectroscopy","FirstCategoryId":"101","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0022285223000607","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"PHYSICS, ATOMIC, MOLECULAR & CHEMICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The infrared spectrum of gaseous methyl bromide (CH3Br) in natural abundance has been analyzed with high resolution, between 1150 and 1700 cm−1. In this spectral region, two fundamental bands, ν2 (A1) and ν5 (E), an overtone 2ν3 (A1) and a combination band ν3 + ν6 (E) occur. The novelty of the present study consists in considering, besides the strong Coriolis and α-interactions coupling the v2 = 1 and v5 = 1 levels, a large variety of anharmonic and rovibrational interactions involving also the v3 = 2 and v3 = v6 = 1 levels. For this latter level, the data set belonging to the ν3 + ν6 combination band has been extended with respect to previous work of Ouahman et al. [Spectrochim. Acta45A (1989) 175–179], to about thousand assigned transitions with . Thanks to the completeness of the theoretical model, the global standard deviation of the reproduction of the experimental wavenumbers in the ν2/ν5 system was greatly improved with respect to the previous high-resolution study of Kwabia Tchana et al. [J. Mol. Spectrosc.228 (2004) 441–452]. For this Coriolis-interacting band system, two different reduction schemes, according to the theory of Stříteská et al. [J. Mol. Spectrosc.256 (2009) 135–140], were applied and were proved to be equally successful.
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.