Millimeter wave and terahertz spectra and global fit of torsion–rotation transitions in the ground, first and second excited torsional states of 13 CH 3 OH methanol

Xu, Li‐Hong; Lees, R. M.; Hao, Yun; Müller, H. S. P.; Endres, Christian; Lewen, Frank; Menten, K. M.

doi:10.1016/j.jms.2014.06.005

Cited by 15 publications

(9 citation statements)

References 36 publications

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“…Further, extensive measurements were carried out in parts of the 1330−1501 GHz region employing a frequency multiplier (Virginia Diode, Inc.) driven by an Agilent E8257D microwave synthesizer as source and the InSb bolometer as detector. This spectrometer was used previously for investigations of CH 3 SH and 13 CH 3 OH [60,61].…”

Section: Rotational Spectra At the Universität Zu Kölnmentioning

confidence: 99%

Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: Low-lying states v8⩽2 of methyl cyanide, CH3CN

Müller

Brown

Drouin

et al. 2015

Journal of Molecular Spectroscopy

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Rotational and rovibrational spectra of methyl cyanide were recorded to analyze interactions in low-lying vibrational states and to construct line lists for radio astronomical observations in space as well as for infrared spectroscopic investigations of planetary atmospheres. The rotational spectra cover large portions of the 36−1627 GHz region. In the infrared (IR), a spectrum was recorded for this study in the region of 2ν 8 around 717 cm −1 with assignments covering 684−765 cm −1. Additional spectra in the ν 8 region were used to validate the analysis. Information on the K level structure of CH 3 CN is almost exclusively obtained from IR spectra, as are basics of the J level structure. The large amount and the high accuracy of the rotational data improves knowledge of the J level structure considerably. Moreover, since these data extend to much higher J and K quantum numbers, they allowed us to investigate for the first time in depth local interactions between these states which occur at high K values. In particular, we have detected several interactions between 8 = 1 and 2. Notably, there is a strong ∆ 8 = ±1, ∆K = 0, ∆l = ±3 Fermi resonance between 8 = 1 −1 and 8 = 2 +2 at K = 14. Pronounced effects in the spectrum are also caused by resonant ∆ 8 = ±1, ∆K = ∓2, ∆l = ±1 interactions between 8 = 1 and 2 at K = 13, l = −1/K = 11, l = 0 and at K = 15, l = +1/K = 13, l = +2. An equivalent resonant interaction occurs between K = 14 of the ground vibrational state and K = 12, l = +1 of 8 = 1 for which we present the first detailed account. A preliminary account was given in an earlier study on the ground vibrational state. Similar resonances were found for CH 3 CCH and, more recently, for CH 3 NC, warranting comparison of the results. From data pertaining to 8 = 2, we also investigated rotational interactions with 4 = 1 as well as ∆ 8 = ±1, ∆K = 0, ∆l = ±3 Fermi interactions between 8 = 2 and 3. We have derived N 2-and self-broadening coefficients for the ν 8 , 2ν 8 − ν 8 , and 2ν 8 bands from previously determined ν 4 values. Subsequently, we determined transition moments and intensities for the three IR bands.

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Section: Rotational Spectra At the Universität Zu Kölnmentioning

confidence: 99%

Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: Low-lying states v8⩽2 of methyl cyanide, CH3CN

Müller

Brown

Drouin

et al. 2015

Journal of Molecular Spectroscopy

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“…The common detection of strong CH 3 OH emission in interstellar environments suggests that in some circumstances it may also be possible to detect maser emission from isotopic methanol species. Theoretical calculations have suggested that the 5 1 -6 0 A + and 2 0 -3 −1 E transitions of 13 CH 3 OH (rest frequencies of approximately 14.300350 and 14.782270 GHz, respectively; Xu et al 2014) are the most promising candidates for isotopic Class II methanol masers (Johns et al 1998). These two transitions are the isotopic analogs of the strongest and most common ClassII methanol maser transitions of CH 3 OH (rest frequencies of 6.668 and 12.178 GHz, respectively).…”

Section: Introductionmentioning

confidence: 99%

¹³CH₃OH Masers Associated With a Transient Phenomenon in a High-mass Young Stellar Object

Chen

Соболев

Breen

et al. 2020

ApJL

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We report the first detection of isotopic methanol ( 13 CH 3 OH) maser emission in interstellar space. The emission was detected toward the high-mass young stellar object G358.93-0.03 during monitoring of a flare in the 6.7 GHz methanol (CH 3 OH) maser emission in this source. We find that the spectral and spatial distribution of the 13 CH 3 OH masers differs from the CH 3 OH masers imaged at the same epoch, contrary to expectations from similarity of their pumping. This conclusively demonstrates that isotopic methanol masers are bright under different physical conditions and suggests that they can provide additional, complementary information to the CH 3 OH masers from the same source. We detect a rapid decay of the 13 CH 3 OH maser lines suggesting that they are transient phenomena (masing for only a few months), likely associated with rapid changes in radiation field due to an accretion burst induced by massive disk fragmentation. Changes in the line flux density are faster than required to achieve equilibrium in the energy level populations, indicating that the pumping of these masers is likely variable.

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“…To the best of our knowledge the lines of methanol measured in the present work have not directly been measured. Xu et al [21], however, reported a global treatment of a large data set including transitions observed at frequencies higher than 1 THz with an accuracy of 50 kHz thus frequency predictions reported in the CDMS database based on this work should be very accurate, to better than 100 kHz. The literature, when available, or predicted center line frequencies are reported in Fig.…”

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confidence: 76%

Broadband terahertz heterodyne spectrometer exploiting synchrotron radiation at megahertz resolution

et al. 2019

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A new spectrometer allowing both high resolution and broadband coverage in the terahertz (THz) domain is proposed. This instrument exploits the heterodyne technique between broadband synchrotron radiation and a quantum cascade laser (QCL) based molecular THz laser that acts as the local oscillator (LO). Proof of principle for exploitation for spectroscopy is provided by the recording of molecular absorptions of hydrogen sulfide (H 2 S) and methanol (CH 3 OH) around 1.073 THz. Ultimately, the spectrometer will enable to cover the 1-4 THz region in 5 GHz windows at Doppler resolution.

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Millimeter wave and terahertz spectra and global fit of torsion–rotation transitions in the ground, first and second excited torsional states of 13 CH 3 OH methanol

Cited by 15 publications

References 36 publications

Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: Low-lying states v8⩽2 of methyl cyanide, CH3CN

Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: Low-lying states v8⩽2 of methyl cyanide, CH3CN

¹³CH₃OH Masers Associated With a Transient Phenomenon in a High-mass Young Stellar Object

Broadband terahertz heterodyne spectrometer exploiting synchrotron radiation at megahertz resolution

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Millimeter wave and terahertz spectra and global fit of torsion–rotation transitions in the ground, first and second excited torsional states of 13 CH 3 OH methanol

Cited by 15 publications

References 36 publications

Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: Low-lying states v8⩽2 of methyl cyanide, CH3CN

Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: Low-lying states v8⩽2 of methyl cyanide, CH3CN

13CH3OH Masers Associated With a Transient Phenomenon in a High-mass Young Stellar Object

Broadband terahertz heterodyne spectrometer exploiting synchrotron radiation at megahertz resolution

Contact Info

Product

Resources

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¹³CH₃OH Masers Associated With a Transient Phenomenon in a High-mass Young Stellar Object