Millimeter wave spectroscopy of cyanoketene (NC–CH=C=O) and an observational search in the ISM

Context. Ketene was detected in the interstellar medium (ISM) in 1977. Until now, only one derivative, the ketenyl radical, has been observed in this medium. Due to its large dipole moment value, cynaoketene is one of the best candidates for possible ketene derivative detection. Aims. To date, the measurements of the rotational spectra have been limited to 60 GHz. The extrapolation of the prediction in the millimeter wave domain is inaccurate and does not permit an unambiguous detection. Methods. The rotational spectra were re-investigated up to 330 GHz. Using the new prediction cyanoketene was sought after in a variety of astronomical sources: NGS 63341, SgrB2(N), and ASAI sources. Results. A total of 1594 transitions were newly assigned and fitted together with those from previous studies, reaching quantum numbers up to J = 82 and Ka = 24. Watson’s asymmetric top Hamiltonian in the Ir representation was used for the analysis; both reductions A and S were tested. Logically, the S reduction gave the best results confirming that the molecule is very close to the prolate limit. Cynaoketene was not found in ISM; upper limits to the column density were derived in each source.

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Submillimeter wave spectroscopy of ethyl isocyanide and its searches in Orion

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731515 ◽

2018 ◽

Vol 610 ◽

pp. A44 ◽

Cited By ~ 6

Author(s):

L. Margulès ◽

B. Tercero ◽

J. C. Guillemin ◽

R. A. Motiyenko ◽

J. Cernicharo

Keyword(s):

Interstellar Medium ◽

Millimeter Wave ◽

Column Density ◽

Submillimeter Wave ◽

Rotational Spectra ◽

Quantum Numbers ◽

Upper Limits ◽

Asymmetric Top ◽

Unambiguous Detection

Context. About 40 cyanide compounds have been detected in the interstellar medium, but only 3 examples of organic isocyanide compounds were observed in this medium. Ethyl isocyanide is one of the best candidates for possible detection. Aim. To date, measurements of rotational spectra are limited to 40 GHz. The extrapolation of the prediction in the millimeter wave domain is inaccurate and does not permit an unambiguous detection. Methods. The rotational spectra were reinvestigated from 0.15 to 1 THz. Using the new prediction, we searched for the compound ethyl isocyanide in Orion KL and Sgr B2. Results. We newly assigned 2906 transitions and fitted these new data with those from previous studies, reaching quantum numbers up to J = 103 and Ka = 30. The asymmetric top Hamiltonian proposed by Watson in the Ir representation was used for the analysis, and both reductions A and S were tested. The search for CH3CH2NC in Sgr B2 (IRAM 30m) and Orion KL (IRAM 30m, ALMA Science Verification) result in a non-detection; upper limits to the column density were derived.

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Submillimeter-wave spectroscopy and the radio-astronomical investigation of propynethial (HC≡CCHS)

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038230 ◽

2020 ◽

Vol 642 ◽

pp. A206 ◽

Cited By ~ 1

Author(s):

L. Margulès ◽

B. A. McGuire ◽

C. J. Evans ◽

R. A. Motiyenko ◽

A. Remijan ◽

...

Keyword(s):

Rotational Spectrum ◽

Star Forming ◽

Rotational Spectra ◽

Dark Clouds ◽

Star Forming Regions ◽

Quantum Numbers ◽

Good Target ◽

Upper Limits ◽

Unambiguous Detection ◽

Sulfur Containing

Context. The majority of sulfur-containing molecules detected in the interstellar medium (ISM) are analogs of oxygen-containing compounds. Propynal was detected in the ISM in 1988, hence propynethial, its sulfur derivative, is a good target for an ISM search. Aims. Our aim is to measure the rotational spectrum of propynethial and use those measurements to search for this species in the ISM. To date, measurements of the rotational spectra of propynethial have been limited to a small number or transitions below 52 GHz. The extrapolation of the prediction to lines in the milimeter-wave domain is inaccurate and does not provide data to permit an unambiguous detection. Methods. The rotational spectrum was re-investigated up to 630 GHz. Using the new prediction lines of propynethial, as well as the related propynal, a variety of astronomical sources were searched, including star-forming regions and dark clouds. Conclusions. A total of 3288 transitions were newly assigned and fit together with those from previous studies, reaching quantum numbers up to J = 107 and Ka = 24. Watson’s symmetric top Hamiltonian in the Ir representation was used for the analysis, because the molecule is very close to the prolate limit. The search for propynethial resulted in a non-detection; upper limits to the column density were derived in each source.

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Observation of the rotational spectra of van der Waals complexes by free jet absorption millimeter wave spectroscopy: pyridine-argon

Chemical Physics Letters ◽

10.1016/0009-2614(96)00977-3 ◽

1996 ◽

Vol 261 (3) ◽

pp. 267-271 ◽

Cited By ~ 109

Author(s):

Sonia Melandri ◽

Gianni Maccaferri ◽

Assimo Maris ◽

Aldo Millemaggi ◽

Walther Caminati ◽

...

Keyword(s):

Millimeter Wave ◽

Van Der Waals ◽

Van Der Waals Complexes ◽

Rotational Spectra ◽

Free Jet ◽

Millimeter Wave Spectroscopy

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Rotational spectra of the H2–HCN cluster observed by millimeter-wave spectroscopy combined with a pulsed supersonic jet technique

The Journal of Chemical Physics ◽

10.1063/1.1377032 ◽

2001 ◽

Vol 115 (11) ◽

pp. 5155-5159 ◽

Cited By ~ 13

Author(s):

Masazumi Ishiguro ◽

Takehiko Tanaka ◽

Kensuke Harada ◽

Christopher J. Whitham ◽

Keiichi Tanaka

Keyword(s):

Millimeter Wave ◽

Supersonic Jet ◽

Rotational Spectra ◽

Millimeter Wave Spectroscopy ◽

Pulsed Supersonic Jet

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The millimeter-wave spectrum and astronomical search of succinonitrile and its vibrational excited states

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935899 ◽

2019 ◽

Vol 629 ◽

pp. A35 ◽

Cited By ~ 3

Author(s):

C. Cabezas ◽

C. Bermúdez ◽

J. D. Gallego ◽

B. Tercero ◽

J. M. Hernández ◽

...

Keyword(s):

Excited States ◽

Millimeter Wave ◽

Dipole Moments ◽

Saturated Hydrocarbon ◽

Wave Spectrum ◽

Rotational Spectrum ◽

Rotational Spectra ◽

Quantum Numbers ◽

Centrifugal Distortion Constants ◽

High Level

Context. Dinitriles with a saturated hydrocarbon skeleton and a −C≡N group at each end can have large electric dipole moments. Their formation can be related to highly reactive radicals such as CH2CN, C2N, or CN. Thus, these saturated dinitriles are potential candidates to be observed in the interstellar medium (ISM). Aims. Our goal is the investigation of the rotational spectrum of one of the simplest dinitriles N≡C−CH2−CH2−C≡N, succinonitrile, whose actual rotational parameters are not precise enough to allow its detection in the ISM. In addition, the rotational spectra for its vibrational excited states will be analysed. Methods. The rotational spectra of succinonitrile was measured in the frequency range 72−116.5 GHz using a new broadband millimeter-wave spectrometer based on radio astronomy receivers with Fast Fourier Transform backends. The identification of the vibrational excited states of succinonitrile was supported by high-level ab initio calculations on the harmonic and anharmonic force fields. Results. A total of 459 rotational transitions with maximum values of J and Ka quantum numbers 70 and 14, respectively, were measured for the ground vibrational state of succinonitrile. The analysis allowed us to accurately determine the rotational, quartic, and sextic centrifugal distortion constants. Up to eleven vibrational excited states, resulting from the four lowest frequency vibrational modes ν13, ν12, ν24, and ν23 were identified. In addition to the four fundamental modes, we observed overtones together with some combination states. The rotational parameters for the ground state were employed to unsuccessfully search for succinonitrile in the cold and warm molecular clouds Orion KL, Sgr B2(N), B1-b, and TMC-1, using the spectral surveys captured by IRAM 30 m at 3 mm and the Yebes 40 m at 1.3 cm and 7 mm.

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