Quadrupole Hyperfine Structure in the Rotational Spectrum of n-PropylIsocyanide

Vormann, Kirsten; Schwarz, R.; Dreizler, H.

doi:10.1515/zna-1988-0315

Cited by 10 publications

(14 citation statements)

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“…Since excited vibrational states have not been taken into consideration the error in the energy difference may well be slightly larger than mentioned above. The residuals quoted in the most recent study (Vormann & Dreizler 1988) for their measurements are frequently much larger than the suggested uncertainties of about 5 kHz suggesting an insufficient set of spectroscopic parameters was used. Moreover, only newly determined rotational and centrifugal distortion parameters were given for the gauche-conformer.…”

Section: Identification Of N-propyl Cyanidementioning

confidence: 94%

“…n-Propyl cyanide frequencies n-Butanenitrile, C 3 H 7 CN, is more commonly known as n-propyl cyanide or n-butyronitrile. Its rotational spectrum has been investigated in the microwave (Hirota 1962;Demaison & Dreizler 1982;Vormann & Dreizler 1988) and in the millimeter wave regions up to 284 GHz (Włodarczak et al 1988). The n indicates the normal isomer with the carbon atoms forming a chain, in contrast to the iso isomer which has a branched structure.…”

Section: Identification Of N-propyl Cyanidementioning

confidence: 99%

“…In the initial fits transition frequencies were taken from all four studies (Hirota 1962;Demaison & Dreizler 1982;Włodarczak et al 1988;Vormann & Dreizler 1988). Two b-type transitions from Włodarczak et al (1988) were omitted from the fits as suggested in the erratum to this paper (Włodarczak et al 1991).…”

Section: Identification Of N-propyl Cyanidementioning

confidence: 99%

“…Two b-type transitions from Włodarczak et al (1988) were omitted from the fits as suggested in the erratum to this paper (Włodarczak et al 1991). On the other hand, transition frequencies not given in Vormann & Dreizler (1988), but deposited at the library of the University of Kiel were obtained from there and included in the fits. Uncertainties of 200, 10, 50, and 5 kHz were assigned to the transitions from Hirota (1962), Demaison & Dreizler (1982), Włodarczak et al (1988), and Vormann & Dreizler (1988), respectively.…”

Section: Identification Of N-propyl Cyanidementioning

confidence: 99%

“…Uncertainties of 200, 10, 50, and 5 kHz were assigned to the transitions from Hirota (1962), Demaison & Dreizler (1982), Włodarczak et al (1988), and Vormann & Dreizler (1988), respectively. Demaison & Dreizler (1982) and Vormann & Dreizler (1988) resolved in part internal rotation of the methyl group or quadrupole splitting of the 14 N nucleus in their laboratory measurements. The methyl internal rotation is unlikely to be resolved in astronomical observations.…”

Section: Identification Of N-propyl Cyanidementioning

confidence: 99%

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Increased complexity in interstellar chemistry: detection and chemical modeling of ethyl formate andn-propyl cyanide in Sagittarius B2(N)

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Garrod

Müller

et al. 2009

A&A

242

300

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Context. In recent years, organic molecules of increasing complexity have been found toward the prolific Galactic center source Sagittarius B2. Aims. We wish to explore the degree of complexity that the interstellar chemistry can reach in star-forming regions. Methods. We carried out a complete line survey of the hot cores Sgr B2(N) and (M) with the IRAM 30 m telescope in the 3 mm range, plus partial surveys at 2 and 1.3 mm. We analyzed this spectral survey in the local thermodynamical equilibrium approximation. We modeled the emission of all known molecules simultaneously, which allows us to search for less abundant, more complex molecules. We compared the derived column densities with the predictions of a coupled gas-phase and grain-surface chemical code.Results. We report the first detection in space of ethyl formate (C 2 H 5 OCHO) and n-propyl cyanide (C 3 H 7 CN) toward Sgr B2(N). The detection of n-propyl cyanide is based on refined spectroscopic parameters derived from combined analyses of available laboratory spectroscopic data. For each molecule, we identified spectral features at the predicted frequencies having intensities compatible with a unique rotation temperature. For an assumed source size of 3 , our modeling yields a column density of 5.4 × 10 16 cm −2 , a temperature of 100 K, and a linewidth of 7 km s −1 for ethyl formate. n-Propyl cyanide is detected with two velocity components having column densities of 1.5 × 10 16 cm −2 and 6.6 × 10 15 cm −2 , respectively, for a source size of 3 , a temperature of 150 K, and a linewidth of 7 km s −1 . The abundances of ethyl formate and n-propyl cyanide relative to H 2 are estimated to be 3.6 × 10 −9 and 1.0 × 10 −9 , respectively. We derived column density ratios of 0.8/15/1 for the related species t-HCOOH/CH 3 OCHO/C 2 H 5 OCHO and 108/80/1 for CH 3 CN/C 2 H 5 CN/C 3 H 7 CN. Our chemical modeling reproduces these ratios reasonably well. It suggests that the sequential, piecewise construction of ethyl and n-propyl cyanide from their constituent functional groups on the grain surfaces is their most likely formation route. Ethyl formate is primarily formed on the grains by adding CH 3 to functional-group radicals derived from methyl formate, although ethanol may also be a precursor. Conclusions. The detection in Sgr B2(N) of the next stage of complexity in two classes of complex molecule, esters and alkyl cyanides, suggests that greater complexity in other classes of molecule may be present in the interstellar medium.

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Section: Identification Of N-propyl Cyanidementioning

confidence: 94%