High-Resolution Infrared Spectroscopy of DC3N in the Stretching Region

Abstract

The perspectives opened by modern ground-based infrared facilities and the forthcoming James Webb Telescope mission have brought a great attention to the ro-vibrational spectra of simple interstellar molecules. In this view, and because of the lack of accurate spectroscopic data, we have investigated the infrared spectrum of deuterated cyanoacetylene (DC3N), a relevant astrochemical species. The ν1, ν2, and ν3 fundamentals as well as their hot-bands were observed in the stretching region (1,500–3,500 cm−1) by means of a Fourier transform infrared spectrometer. Supplementary measurements were performed at millimeter-wavelengths (243–295 GHz) with a frequency-modulation spectrometer equipped with a furnace, that allowed to probe pure rotational transitions in the investigated stretching states. Furthermore, since HC3N is observed as by-product in our spectra and suffers from the same deficiency of accurate infrared data, its ro-vibrational features have been analyzed as well. The combined analysis of both rotational and ro-vibrational data allowed us to determine precise spectroscopic constants that can be used to model the infrared spectra of DC3N and HC3N. The importance of accurate molecular data for the correct modeling of proto-planetary disks and exoplanetary atmospheres is then discussed.

Hunting for interstellar molecules: rotational spectra of reactive species

“…Since the cell and oven lengths are different, the heating is inhomogeneously distributed along the cell, with the pyrolysis reaction being confined to the 90 cm directly heated by the oven. To increase the length of the reactive area, a double-pass configuration is arranged, 32 with the effective absorption path of the pyrolysis products increasing to, at least, 1.8 m. For both apparatuses, in view of the unstable nature of the target molecules, measurements are performed in dynamic conditions, i.e. a tenuous flow of fresh pyrolysis products is continuously provided by the vacuum system.…”

Laboratory spectroscopy of allylimine and tentative detection towards the G+0.693-0.027 molecular cloud

“…The measurements were performed in a quartz absorption cell surrounded by a 90 cm long tubular oven, using the same set-up recently described by Jiang et al (2021). The optical elements of the spectrometer were arranged in a double-pass configuration (for further details, see e.g.…”

Detectable Abundance of Cyanoacetylene (HC$_3$N) Predicted on Reduced Nitrogen-Rich Super-Earth Atmospheres

“…There existed no comprehensive IR line list for HC 3 N applicable for a broad range of temperatures. The experimental and theoretical information is rather scarce for HC 3 N, especially in IR, only for the room temperature (Bénilan et al 2006;Jolly et al 2007;Douin et al 2015;Bizzocchi et al 2017;Jiang et al 2021). For this study, we have combined spectroscopic data available for HC 3 N in the literature to construct a line list as a best estimate of the opacity of HC 3 N in IR.…”

“…We used the program PGOPHER (Western 2017) to generate energies and Einstein coefficients of HC 3 N. Spectroscopic constants of 2ν 6 , ν 5 + ν 7 , ν 6 + ν 7 , ν 6 + 2ν 7 , ν 1 , ν 2 , ν 3 , ν 1 + ν 7 , ν 2 + ν 7 and ν 3 + ν 7 were taken from the high-resolution IR studies by Bizzocchi et al (2017); Jiang et al (2021). Other states of HC 3 N from this IR region have not been characterized experimentally.…”

“…Experimentally, the IR intensities of HC 3 N was studied in Bénilan et al (2006); Douin et al (2015). High-resolution spectroscopic analyses were reported by Bizzocchi et al (2017); Jiang et al (2021). Swain et al (2021) analyzed of Hubble data of GJ 1132 b transmission spectra and find 0.5% concentrations of both HCN and CH 4 in an atmosphere with low mean molecular mass, implying the atmosphere is hydrogen-dominated.…”