Dataset Information

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

ABSTRACT: 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 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 exicted states will be analyzed. 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 ? 13, ? 12, ? 24 and ? 23 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 30m at 3mm and the Yebes 40m at 1.3cm and 7mm. Conclusions:

SUBMITTER: Cabezas C

PROVIDER: S-EPMC6726483 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The millimeter-wave spectrum and astronomical search of succinonitrile and its vibrational excited states <sup>★</sup>.

Cabezas C C Bermúdez C C Gallego J D JD Tercero B B Hernández J M JM Tanarro I I Herrero V J VJ Doménech J L JL Cernicharo J J

Astronomy and astrophysics 20190902

<h4>Context</h4>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 CH<sub>2</sub>CN, C<sub>2</sub>N or CN. Thus, these saturated dinitriles are potential candidates to be observed in the ISM.<h4>Aims</h4>Our goal is the investigation of the rotational spectrum of one of the simplest dinitriles N≡C-CH<sub>2</sub>-CH<sub>2</sub>-C≡N, succinonitrile, whose actual rot ...[more]

PMID: 31485081

Similar Datasets

Project description:C-cyanomethanimine (HNCHCN), existing in the two Z and E isomeric forms, is a key prebiotic molecule, but, so far, only the E isomer has been detected toward the massive star-forming region. Sagittarius B2(N) using transitions in the radio wavelength domain.With the aim of detecting HNCHCN in Sun-like-star forming regions, the laboratory investigation of its rotational spectrum has been extended to the millimeter-/submillimeter-wave (mm-/submm-) spectral window in which several unbiased spectral surveys have been already carried out.High-resolution laboratory measurements of the rotational spectrum of C-cyanomethanimine were carried out in the 100-420 GHz range using a frequency-modulation absorption spectrometer. We then searched for the C-cyanomethanimine spectral features in the mm-wave range using the high-sensitivity and unbiased spectral surveys obtained with the IRAM 30-m antenna in the ASAI context, the earliest stages of star formation from starless to evolved Class I objects being sampled.For both the Z and E isomers, the spectroscopic work has led to an improved and extended knowledge of the spectroscopic parameters, thus providing accurate predictions of the rotational signatures up to ~700 GHz. So far, no C-cyanomethanimine emission has been detected toward the ASAI targets, and upper limits of the column density of ~ 1011-1012 cm-2 could only be derived. Consequently, the C-cyanomethanimine abundances have to be less than a few 10-10 for starless and hot-corinos. A less stringent constraint, ? 10-9, is obtained for shocks sites.The combination of the upper limits of the abundances of C-cyanomethanimine together with accurate laboratory frequencies up to ~ 700 GHz poses the basis for future higher sensitivity searches around Sun-like-star forming regions. For compact (typically less than 1?) and chemically enriched sources such as hot-corinos, the use of interferometers as NOEMA and ALMA in their extended configurations are clearly needed.

Project description:For all the amides detected in the interstellar medium (ISM), the corresponding nitriles or isonitriles have also been detected in the ISM, some of which have relatively high abundances. Among the abundant nitriles for which the corresponding amide has not yet been detected is cyanoacetylene (HCCCN), whose amide counterpart is propiolamide (HCCC(O)NH2). With the aim of supporting searches for this amide in the ISM, we provide a complete rotational study of propiolamide from 6 GHz to 440 GHz. Time-domain Fourier transform microwave (FTMW) spectroscopy under supersonic expansion conditions between 6 GHz and 18 GHz was used to accurately measure and analyze ground-state rotational transitions with resolved hyperfine structure arising from nuclear quadrupole coupling interactions of the 14N nucleus. We combined this technique with the frequency-domain room-temperature millimeter wave and submillimeter wave spectroscopies from 75 GHz to 440 GHz in order to record and assign the rotational spectra in the ground state and in the low-lying excited vibrational states. We used the ReMoCA spectral line survey performed with the Atacama Large Millimeter/submillimeter Array toward the star-forming region Sgr B2(N) to search for propiolamide. We identified and measured more than 5500 distinct frequency lines of propiolamide in the laboratory. These lines were fitted using an effective semi-rigid rotor Hamiltonian with nuclear quadrupole coupling interactions taken into consideration. We obtained accurate sets of spectroscopic parameters for the ground state and the three low-lying excited vibrational states. We report the nondetection of propiolamide toward the hot cores Sgr B2(N1S) and Sgr B2(N2). We find that propiolamide is at least 50 and 13 times less abundant than acetamide in Sgr B2(N1S) and Sgr B2(N2), respectively, indicating that the abundance difference between both amides is more pronounced by at least a factor of 8 and 2, respectively, than for their corresponding nitriles. Although propiolamide has yet to be included in astrochemical modeling networks, the observed upper limit to the ratio of propiolamide to acetamide seems consistent with the ratios of related species as determined from past simulations. The comprehensive spectroscopic data presented in this paper will aid future astronomical searches.

Dataset Information

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

Publications

The millimeter-wave spectrum and astronomical search of succinonitrile and its vibrational excited states <sup>★</sup>.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets