The 130–500 GHz rotational spectroscopy of cyanopyrazine (C4H3N2-CN)

Esselman, Brian J.; Zdanovskaia, Maria A.; Smith, Houston; Woods, R. Claude; McMahon, Robert J.

doi:10.1016/j.jms.2022.111703

Cited by 7 publications

(15 citation statements)

References 36 publications

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“…The recently expanded frequency range of our instrument allowed us to measure the rotational spectrum of 2-furonitrile up to 750 GHz, a frequency coverage well beyond that used in some of our previous works on cyanoarenes (up to 375 GHz − or up to 500 GHz , ). Spectral coverage up to 750 GHz is the nearly optimal range at ambient laboratory temperature (Figure ), capturing nearly all of the most intense a - and b -type transitions for 2-furonitrile.…”

Section: Resultsmentioning

confidence: 99%

“…The spectral coverage allows the observation of the K a = 0 series transitions with a value of J ″ + 1 = 42 near 140 GHz, increasing to J ″ + 1 = 225 just below 750 GHz. Though the population of these transitions is quite small and the highest J ″ + 1 of a K a = 0 transition included in the data set is 190, the spectral range is comparable to that of cyanopyrazine . This range of J ″ + 1 (and the resulting range of K a ) quantum numbers provides a wealth of spectroscopic information on the centrifugal distortion and consequently necessitates a partial octic Hamiltonian to adequately model the spectrum …”

Section: Resultsmentioning

confidence: 99%

“…A unifying feature of the spectra of cyanoarenes is the a - and/or b -axis Coriolis-coupled dyad of their two lowest-energy fundamental states, the out-of-plane and in-plane vibrations of the nitrile group. As with these previous studies, − we report the rotational spectra of the ground vibrational state and the Coriolis-coupled dyad of the two lowest-energy fundamental vibrational modes (ν 24 and ν 17 ). We also present a preliminary analysis of the third fundamental mode, ν 23 .…”

Section: Introductionmentioning

confidence: 82%

“…A commercial sample of 2-furonitrile was used without purification for all spectroscopic measurements. Using a millimeter-wave spectrometer that has been previously described, ,, the rotational spectrum of 2-furonitrile was collected from 140 to 230 and from 235 to 750 GHz, in a continuous flow at room temperature, with sample pressures of 3–8 mTorr. The complete spectrum from 140 to 750 GHz was obtained automatically over ∼2 weeks given the following experimental parameters: 0.6 MHz/s sweep rate, 10 ms time constant, and 50 kHz AM and 500 kHz FM modulation in a tone burst design.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Cyano substitution of benzene and naphthalene was critical to this conclusion, as neither parent species has a permanent dipole moment. The recent works on cyanoarenes may lead to the eventual detection of these species, − providing similarly strong evidence for the presence of their parent heterocycles (pyridine, pyrimidine, and pyrazine). To provide similar laboratory data for the astronomical community, we investigated the rotational spectra of the two regioisomeric furonitriles (cyanofurans) (Figure ).…”

Section: Introductionmentioning

confidence: 94%

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Millimeter-Wave and High-Resolution Infrared Spectroscopy of 2-Furonitrile─A Highly Polar Substituted Furan

et al. 2023

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The rotational spectrum of 2-furonitrile (2-cyanofuran) has been obtained from 140 to 750 GHz, capturing its most intense rotational transitions at ambient temperature. 2-Furonitrile is one of two isomeric cyano-substituted furan derivatives, both of which possess a substantial dipole moment due to the cyano group. The large dipole of 2-furonitrile allowed over 10 000 rotational transitions of its ground vibrational state to be observed and least-squares fit to partial octic, A-and S-reduced Hamiltonians with low statistical uncertainty (σ fit = 40 kHz). The high-resolution infrared spectrum, obtained at the Canadian Light Source, allowed for accurate and precise determination of the band origins of its three lowest-energy fundamental modes (ν 24 , ν 17 , and ν 23 ). Similar to other cyanoarenes, the first two fundamental modes (ν 24, A″, and ν 17 , A′, for 2-furonitrile) form an a-and b-axis Coriolis-coupled dyad. More than 7000 transitions from each of these fundamental states were fit to an octic A-reduced Hamiltonian (σ fit = 48 kHz), and the combined spectroscopic analysis determines fundamental energies of 160.1645522 (26) cm −1 and 171.9436561 (25) cm −1 for ν 24 and ν 17 , respectively. The least-squares fitting of this Coriolis-coupled dyad required 11 coupling terms,J , and F ac K . Using both the rotational and high-resolution infrared spectra, a preliminary least-squares fit was obtained for ν 23 , providing its band origin of 456.7912716 (57) cm −1 . The transition frequencies and spectroscopic constants provided in this work, when combined with theoretical or experimental nuclear quadrupole coupling constants, will provide the foundation for future radioastronomical searches for 2-furonitrile across the frequency range of currently available radiotelescopes.

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