Laboratory spectroscopic study of the ${}^{15}$N isotopomers of cyanamide, H${}_2$NCN, and a search for them toward IRAS 16293$-$2422 B

Abstract

Cyanamide is one of the few interstellar molecules containing two chemically different N atoms. It was detected recently toward the solar-type protostar IRAS 16293-2422 B together with H${}_2$N${}^{13}$CN and HDNCN in the course of the Atacama Large Millemeter/submillimeter Array (ALMA) Protostellar Interferometric Line Survey (PILS). The detection of the 15N isotopomers or the determination of upper limits to their column densities was hampered by the lack of accurate laboratory data at the frequencies of the survey. We wanted to determine spectroscopic parameters of the ${}^{15}$N isotopomers of cyanamide that are accurate enough for predictions well into the submillimeter region and to search for them in the PILS data. We investigated the laboratory rotational spectra of H${}_2^{15}$NCN and H${}_2$NC${}^{15}$N in the selected region between 192 and 507~GHz employing a cyanamide sample in natural isotopic composition. Additionally, we recorded transitions of H${}_2$N${}^{13}$CN. We obtained new or improved spectroscopic parameters for the three isotopic species. Neither of the ${}^{15}$N isotopomers of cyanamide were detected unambiguously in the PILS data. Two relatively clean lines can be tentatively assigned to H${}_2^{15}$NCN. If confirmed, their column densities would imply a low ${}^{14}$N/${}^{15}$N ratio for cyanamide toward this source. The resulting line lists should be accurate enough for observations up to about 1 THz. More sensitive observations, potentially at different frequencies, may eventually lead to the astronomical detection of these isotopic species.

arXiv commentAstron. Astrophys., 8 pages; paper appeared; CDMS links corrected

References in corpus (17)

• The Cologne Database for Molecular Spectroscopy, CDMS, in the Virtual Atomic and Molecular Data Centre, VAMDC
• Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)
• The ALMA Protostellar Interferometric Line Survey (PILS): First results from an unbiased submillimeter wavelength line survey of the Class 0 protostellar binary IRAS 16293-2422 with ALMA
• A 2 mm spectral line survey of the starburst galaxy NGC 253
• The ALMA-PILS survey: Isotopic composition of oxygen-containing complex organic molecules toward IRAS 16293-2422B
• Exploring molecular complexity with ALMA (EMoCA): Alkanethiols and alkanols in Sagittarius B2(N2)
• The ALMA-PILS survey: First detections of deuterated formamide and deuterated isocyanic acid in the interstellar medium
• The ALMA-PILS survey: Complex nitriles towards IRAS 16293--2422
• A lambda = 1.3 mm and 2 mm molecular line survey towards M82
• A spectral survey of the Star Forming Core of the Orion Nebula from 455 -- 507 GHz
• Detection of (15)NNH+ in L1544: non-LTE modelling of dyazenilium hyperfine line emission and accurate (14)N/(15)N values
• The ALMA-PILS survey: Formaldehyde deuteration in warm gas on small scales toward IRAS 16293-2422 B
• First detection of cyanamide (NH${}_2$CN) towards solar-type protostars
• ALMA observations of the young protostellar system Barnard 1b: signatures of an incipient hot corino in B1b-S
• Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: low-lying states $v_8\le 2$ of methyl cyanide, CH${}_3$CN
• Observations of nitrogen isotope fractionation in deeply embedded protostars
• Submillimeter spectroscopy of H${}_2$C${}^{17}$O and a revisit of the rotational spectra of H${}_2$C${}^{18}$O and H${}_2$C${}^{16}$O

Cited by in corpus (7)

• Ingredients for Solar-like Systems: protostar IRAS 16293-2422 B versus comet 67P/Churyumov-Gerasimenko
• Reexploring Molecular Complexity with ALMA: Insights into chemical differentiation from the molecular composition of hot cores in Sgr B2(N2)
• Millimetre-wave laboratory study of glycinamide and search for it with ALMA toward Sagittarius B2(N)
• Rotation-tunneling spectrum and astrochemical modeling of dimethylamine, CH${}_3$NHCH${}_3$, and searches for it in space
• The salty emission of the intermediate-mass AGB star OH 30.1 -0.7
• (Sub-)millimeter-wave spectroscopy of gauche-propanal
• The Reaction between Atomic Carbon and Molecular Nitrogen as a Source of Cyanamide and Carbodiimide on Interstellar Ices