The millimeter-wave spectrum of ethynylisocyanide (HCCNC)

Guarnieri, A.; Hinze, R.; Krüger, Michael; Zerbe-Foese, H.; Lentz, Dieter; Preugschat, Dagmar

doi:10.1016/0022-2852(92)90091-2

Cited by 30 publications

(27 citation statements)

References 12 publications

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“…The line parameters are taken from the CDMS (Müller et al 2005) for CH 3 CN, HC 3 N and C 3 N, and from the JPL (Pickett et al 1998) for CH 3 NC, HC 2 NC and HNC 3 . Original spectroscopic data come from Müller et al (2009) for CH 3 CN, Thorwirth et al (2000) for HC 3 N, Gottlieb et al (1983) for C 3 N, Bauer & Bogey (1970) for CH 3 NC, Guarnieri et al (1992) for HC 2 NC, and Hirahara et al (1993) In this section, we quantify the error made when using rotational diagrams to derive column densities and abundances in moderately sub thermal excitation regimes such as those found in the PDR position (∼6 × 10 4 cm −3 ). We built the rotational diagrams assuming that the line emission is optically thin, i.e.…”

Section: Appendix A: Observational Tablesmentioning

confidence: 99%

The IRAM-30 m line survey of the Horsehead PDR

Gratier

Pety

Guzmán

et al. 2013

A&A

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Context. Complex (iso-)nitrile molecules, such as CH 3 CN and HC 3 N, are relatively easily detected in our Galaxy and in other galaxies. Aims. We aim at constraining their chemistry through observations of two positions in the Horsehead edge: the photo-dissociation region (PDR) and the dense, cold, and UV-shielded core just behind it. Methods. We systematically searched for lines of CH 3 CN, HC 3 N, C 3 N, and some of their isomers in our sensitive unbiased line survey at 3, 2, and 1 mm. We stacked the lines of C 3 N to improve the detectability of this species. We derived column densities and abundances through Bayesian analysis using a large velocity gradient radiative transfer model. Results. We report the first clear detection of CH 3 NC at millimeter wavelength. We detected 17 lines of CH 3 CN at the PDR and 6 at the dense core position, and we resolved its hyperfine structure for 3 lines. We detected 4 lines of HC 3 N, and C 3 N is clearly detected at the PDR position. We computed new electron collisional rate coefficients for CH 3 CN, and we found that including electron excitation reduces the derived column density by 40% at the PDR position, where the electron density is 1-5 cm −3 . While CH 3 CN is 30 times more abundant in the PDR (2.5 × 10 −10 ) than in the dense core (8 × 10 −12 ), HC 3 N has similar abundance at both positions (8 × 10 −12 ). The isomeric ratio CH 3 NC/CH 3 CN is 0.15 ± 0.02. Conclusions. The significant amount of complex (iso-)nitrile molecule in the UV illuminated gas is puzzling as the photodissociation is expected to be efficient. This is all the more surprising in the case of CH 3 CN, which is 30 times more abundant in the PDR than in the dense core. In this case, pure gas phase chemistry cannot reproduce the amount of CH 3 CN observed in the UV-illuminated gas. We propose that CH 3 CN gas phase abundance is enhanced when ice mantles of grains are destroyed through photo-desorption or thermal-evaporation in PDRs, and through sputtering in shocks.

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Section: Appendix A: Observational Tablesmentioning

confidence: 99%

The IRAM-30 m line survey of the Horsehead PDR

Gratier

Pety

Guzmán

et al. 2013

A&A

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“…To obtain an upper limit for its column density we assumed the same physical components as those of Esplugues et al (2013b). Spectroscopic parameters were derived by fitting the lines reported by Guarnieri et al (1992); the dipole moment was taken from Gripp et al (2000). We obtained an upper limit to the HCCNC column density of ≤(3 ± 1) × 10 13 cm −2 .…”

Section: Referencesmentioning

confidence: 99%

Laboratory characterization and astrophysical detection of vibrationally excited states of vinyl cyanide in Orion-KL

López

Tercero

Kisiel

et al. 2014

A&A

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Context. We perform a laboratory characterization in the 18-1893 GHz range and astronomical detection between 80-280 GHz in Orion-KL with IRAM-30 m of CH 2 CHCN (vinyl cyanide) in its ground and vibrationally excited states. Aims. Our aim is to improve the understanding of rotational spectra of vibrationally excited vinyl cyanide with new laboratory data and analysis. The laboratory results allow searching for these excited state transitions in the Orion-KL line survey. Furthermore, rotational lines of CH 2 CHCN contribute to the understanding of the physical and chemical properties of the cloud. Methods. Laboratory measurements of CH 2 CHCN made on several different frequency-modulated spectrometers were combined into a single broadband 50-1900 GHz spectrum and its assignment was confirmed by Stark modulation spectra recorded in the 18-40 GHz region and by ab-initio anharmonic force field calculations. For analyzing the emission lines of vinyl cyanide detected in Orion-KL we used the excitation and radiative transfer code (MADEX) at LTE conditions. Results. Detailed characterization of laboratory spectra of CH 2 CHCN in nine different excited vibrational states: 11 = 1, 15 = 1, 11 = 2, 10 = 1 ⇔ ( 11 = 1, 15 = 1), 11 = 3/ 15 = 2/ 14 = 1, ( 11 = 1, 10 = 1) ⇔ ( 11 = 2, 15 = 1), 9 = 1, ( 11 = 1, 15 = 2) ⇔ ( 10 = 1, 15 = 1) ⇔ ( 11 = 1, 14 = 1), and 11 = 4 are determined, as well as the detection of transitions in the 11 = 2 and 11 = 3 states for the first time in Orion-KL and of those in the 10 = 1 ⇔ ( 11 = 1, 15 = 1) dyad of states for the first time in space. The rotational transitions of the ground state of this molecule emerge from four cloud components of hot core nature, which trace the physical and chemical conditions of high mass star forming regions in the Orion-KL Nebula. The lowest energy vibrationally excited states of vinyl cyanide, such as 11 = 1 (at 328.5 K), 15 = 1 (at 478.6 K), 11 = 2 (at 657.8 K), the 10 = 1 ⇔ ( 11 = 1, 15 = 1) dyad (at 806.4/809.9 K), and 11 = 3 (at 987.9 K), are populated under warm and dense conditions, so they probe the hottest parts of the Orion-KL source. The vibrational temperatures derived for the 11 = 1, 11 = 2, and 15 = 1 states are 252 ± 76 K, 242 ± 121 K, and 227 ± 68 K, respectively; all of them are close to the mean kinetic temperature of the hot core component (210 K). The total column density of CH 2 CHCN in the ground state is (3.0 ± 0.9) × 10 15 cm −2 . We report the detection of methyl isocyanide (CH 3 NC) for the first time in Orion-KL and a tentative detection of vinyl isocyanide (CH 2 CHNC). We also give column density ratios between the cyanide and isocyanide isomers, obtaining a N(CH 3 NC)/N(CH 3 CN) ratio of 0.002. Conclusions. Laboratory characterization of many previously unassigned vibrationally excited states of vinyl cyanide ranging from microwave to THz frequencies allowed us to detect these molecular species in Orion-KL. Column density, rotational and vibrational temperatures for CH 2 CHCN in their ground and excited states, and the isotopolo...

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“…The diagonal rovibrational energies are given by [4] H v 0 ϭ H 0 [5] and l ϭ t l t . [6] The main rotational l-type resonance terms are given by ͗l t ͉H͉l t Ϯ 2͘ ϭ [8] where ␦ st is the Kronecker symbol and…”

Section: Rovibrational Energy Matrixmentioning

confidence: 99%

“…Isocyanoacetylene has been investigated by millimeter-wave spectroscopy (4) in the ground state and the v 4 ϭ 1, v 5 ϭ 1, v 6 ϭ 1, and v 7 ϭ 1 excited vibrational states. Fourier transform infrared spectra have been recorded between 350 and 5000 cm Ϫ1 (5).…”

Section: Introductionmentioning

confidence: 99%