Synchrotron radiation far infrared spectrum of the astrophysically significant Ethanol (CH3CH2OH) molecule in the gauche states in the vibrational ground state and other infrared observations
{"title":"Synchrotron radiation far infrared spectrum of the astrophysically significant Ethanol (CH3CH2OH) molecule in the gauche states in the vibrational ground state and other infrared observations","authors":"Indranath Mukhopadhyay","doi":"10.1016/j.infrared.2024.105534","DOIUrl":null,"url":null,"abstract":"<div><p>In this communication, the analyses of synchrotron radiation far infrared (FIR) spectrum corresponding to the gauche- (<span><math><mrow><msub><mi>e</mi><mn>1</mn></msub><mi>a</mi><mi>n</mi><mi>d</mi><msub><mi>o</mi><mn>1</mn></msub></mrow></math></span>) states of Ethyl Alcohol are reported. Detailed assignments have been performed for b-type transitions for K values ranging from 5 to 32 and up to a maximum J value of 50. The assignments confirmed the earlier microwave (MW) and millimeter wave (MMW) spectroscopic results. The transition wavenumbers have been used to determine the term values for the gauche-states involved for all the K and J values for which observation has been made. About 2000 spectral lines have been assigned, including some accurately calculated lines that fall in the MW and MMW regions. Although transitions between the trans-species and gauche species are not allowed in Ethanol, many resonances and level crossings of energy levels cause forbidden transitions. One such system of level crossings between <span><math><mrow><mi>K</mi><mo>=</mo><mn>10</mn><msub><mi>o</mi><mn>1</mn></msub></mrow></math></span> and <span><math><mrow><mn>12</mn><mi>e</mi><msub><mi>e</mi><mn>0</mn></msub><mn>0</mn></mrow></math></span> has been analyzed in detail, and the interaction coefficient determined. The state mixing seems quite strong and causes forbidden transitions <span><math><mrow><mo>(</mo><mi>Δ</mi><mi>K</mi><mo>=</mo><mn>0</mn><mo>,</mo><mn>2</mn><mo>,</mo><mn>3</mn><mo>)</mo></mrow></math></span>, including transitions for <span><math><mrow><mi>trans</mi><mo>↔</mo><mi>g</mi><mi>a</mi><mi>u</mi><mi>c</mi><mi>h</mi><mi>e</mi></mrow></math></span>, have been found. In addition, many new strong transitions have been assigned, which belong to the trans-species. To extend our work to higher wave numbers to facilitate observations made by the infrared detector on board the James Webb Space Telescope (<em>JWST</em>), the analysis of the torsional fundamental band transitions (around <span><math><mrow><mn>220</mn><msup><mrow><mi>cm</mi></mrow><mrow><mo>-</mo><mn>1</mn></mrow></msup></mrow></math></span>) for <span><math><mrow><msub><mi>o</mi><mn>2</mn></msub><mo>←</mo><msub><mi>e</mi><mn>0</mn></msub></mrow></math></span> and <span><math><mrow><msub><mi>o</mi><mn>2</mn></msub><mo>←</mo><msub><mi>e</mi><mn>1</mn></msub></mrow></math></span> has been taken up. Some of the assignments are discussed here. Lastly, the lower-lying vibrational bands centered around <span><math><mrow><mn>425</mn><msup><mrow><mi>cm</mi></mrow><mrow><mo>-</mo><mn>1</mn></mrow></msup></mrow></math></span> (CCO– bending mode) and the band at around <span><math><mrow><mn>800</mn><msup><mrow><mi>cm</mi></mrow><mrow><mo>-</mo><mn>1</mn></mrow></msup></mrow></math></span> (<span><math><mrow><msub><mrow><mi>CH</mi></mrow><mn>3</mn></msub><mo>-</mo></mrow></math></span> rocking mode) have been recorded. The CCO bending band shows an unmistakable parallel character for the <em>trans</em>-species. The assignment work on the CCO-bending band is in progress, and the assignments for <span><math><mrow><mi>K</mi><mo>=</mo><mn>0</mn><mi>a</mi><mi>n</mi><mi>d</mi><mi>K</mi><mo>=</mo><mn>1</mn><mo>(</mo><mo>+</mo><mi>a</mi><mi>n</mi><mi>d</mi><mo>-</mo><mo>)</mo></mrow></math></span> are included in this report. Accurate term values for the CCO-bending mode could be obtained. The results allowed the determination of the leading rotational constants for the <em>trans</em>-species in the excited vibrational state of the CCO-bending state. The complete known assigned lines of about 16,000 lines for the parent isotopomer and about 650 lines for 13 <span><math><msub><mrow><mo>-</mo><mi>C</mi></mrow><mn>1</mn></msub></math></span> and 13−<span><math><msub><mi>C</mi><mn>2</mn></msub></math></span> (see graphical abstract) substituted Ethanol isotopomers are gathered in <span><span>Appendix I and II</span></span>, respectively. These atlases should be a valuable tool for further energy level analysis and astronomical detection of Ethanol in interstellar space.</p></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":null,"pages":null},"PeriodicalIF":3.1000,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Infrared Physics & Technology","FirstCategoryId":"101","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1350449524004183","RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"INSTRUMENTS & INSTRUMENTATION","Score":null,"Total":0}
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Abstract
In this communication, the analyses of synchrotron radiation far infrared (FIR) spectrum corresponding to the gauche- () states of Ethyl Alcohol are reported. Detailed assignments have been performed for b-type transitions for K values ranging from 5 to 32 and up to a maximum J value of 50. The assignments confirmed the earlier microwave (MW) and millimeter wave (MMW) spectroscopic results. The transition wavenumbers have been used to determine the term values for the gauche-states involved for all the K and J values for which observation has been made. About 2000 spectral lines have been assigned, including some accurately calculated lines that fall in the MW and MMW regions. Although transitions between the trans-species and gauche species are not allowed in Ethanol, many resonances and level crossings of energy levels cause forbidden transitions. One such system of level crossings between and has been analyzed in detail, and the interaction coefficient determined. The state mixing seems quite strong and causes forbidden transitions , including transitions for , have been found. In addition, many new strong transitions have been assigned, which belong to the trans-species. To extend our work to higher wave numbers to facilitate observations made by the infrared detector on board the James Webb Space Telescope (JWST), the analysis of the torsional fundamental band transitions (around ) for and has been taken up. Some of the assignments are discussed here. Lastly, the lower-lying vibrational bands centered around (CCO– bending mode) and the band at around ( rocking mode) have been recorded. The CCO bending band shows an unmistakable parallel character for the trans-species. The assignment work on the CCO-bending band is in progress, and the assignments for are included in this report. Accurate term values for the CCO-bending mode could be obtained. The results allowed the determination of the leading rotational constants for the trans-species in the excited vibrational state of the CCO-bending state. The complete known assigned lines of about 16,000 lines for the parent isotopomer and about 650 lines for 13 and 13− (see graphical abstract) substituted Ethanol isotopomers are gathered in Appendix I and II, respectively. These atlases should be a valuable tool for further energy level analysis and astronomical detection of Ethanol in interstellar space.
期刊介绍:
The Journal covers the entire field of infrared physics and technology: theory, experiment, application, devices and instrumentation. Infrared'' is defined as covering the near, mid and far infrared (terahertz) regions from 0.75um (750nm) to 1mm (300GHz.) Submissions in the 300GHz to 100GHz region may be accepted at the editors discretion if their content is relevant to shorter wavelengths. Submissions must be primarily concerned with and directly relevant to this spectral region.
Its core topics can be summarized as the generation, propagation and detection, of infrared radiation; the associated optics, materials and devices; and its use in all fields of science, industry, engineering and medicine.
Infrared techniques occur in many different fields, notably spectroscopy and interferometry; material characterization and processing; atmospheric physics, astronomy and space research. Scientific aspects include lasers, quantum optics, quantum electronics, image processing and semiconductor physics. Some important applications are medical diagnostics and treatment, industrial inspection and environmental monitoring.