Microwave Spectroscopy of Vinyl Cyanide, Taking into Account the Hyperfine Structure

Баскаков, О. І.; Dyubko, S. F.; Ilyushin, V. V.; Efimenko, M. N.; Ефремов, В. Н.; Podnos, S.V.; Alekseev, E. A.

doi:10.1006/jmsp.1996.0188

Cited by 22 publications

(61 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The entries were based on data described in Müller et al (2008). This work includes in particular laboratory data from Gerry & Winnewisser (1973), Baskakov (1996), and Cazzoli & Kisiel (1988) providing rest frequencies for the main isotopic species in the range of our line survey. In the case of the 13 C isotopologues, Colmont et al (1997) cover additional frequency ranges similar to the ones of our survey.…”

Section: Vinyl Cyanide C 2 H 3 Cnmentioning

confidence: 99%

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Беллоче

Müller

Menten

et al. 2013

A&A

375

523

View full text Add to dashboard Cite

Context. The discovery of amino acids in meteorites fallen to Earth and the detection of glycine, the simplest of them, in samples returned from a comet to Earth strongly suggest that the chemistry of the interstellar medium is capable of producing such complex organic molecules and that they may be widespread in our Galaxy. Aims. Our goal is to investigate the degree of chemical complexity that can be reached in the interstellar medium, in particular in dense star-forming regions. Methods. We performed an unbiased, spectral line survey toward Sgr B2(N) and (M), two regions where high-mass stars are formed, with the IRAM 30 m telescope in the 3 mm atmospheric transmission window. Partial surveys at 2 and 1.3 mm were performed in parallel. The spectra were analyzed with a simple radiative transfer model that assumes local thermodynamic equilibrium but takes optical depth effects into account. Results. About 3675 and 945 spectral lines with a peak signal-to-noise ratio higher than 4 are detected at 3 mm toward Sgr B2(N) and (M), i.e. about 102 and 26 lines per GHz, respectively. This represents an increase by about a factor of two over previous surveys of Sgr B2. About 70% and 47% of the lines detected toward Sgr B2(N) and (M) are identified and assigned to 56 and 46 distinct molecules as well as to 66 and 54 less abundant isotopologues of these molecules, respectively. In addition, we report the detection of transitions from 59 and 24 catalog entries corresponding to vibrationally or torsionally excited states of some of these molecules, respectively, up to a vibration energy of 1400 cm −1 (2000 K). Excitation temperatures and column densities were derived for each species but should be used with caution. The rotation temperatures of the detected complex molecules typically range from ∼50 to 200 K. Among the detected molecules, aminoacetonitrile, n-propyl cyanide, and ethyl formate were reported for the first time in space based on this survey, as were five rare isotopologues of vinyl cyanide, cyanoacetylene, and hydrogen cyanide. We also report the detection of transitions from within twelve new vibrationally or torsionally excited states of known molecules. Absorption features produced by diffuse clouds along the line of sight are detected in transitions with low rotation quantum numbers of many simple molecules and are modeled with ∼30-40 velocity components with typical linewidths of ∼3-5 km s −1 . Conclusions. Although the large number of unidentified lines may still allow future identification of new molecules, we expect most of these lines to belong to vibrationally or torsionally excited states or to rare isotopologues of known molecules for which spectroscopic predictions are currently missing. Significant progress in extending the inventory of complex organic molecules in Sgr B2(N) and deriving tighter constraints on their location, origin, and abundance is expected in the near future thanks to an ongoing spectral line survey at 3 mm with ALMA in its cycles 0 and 1. The present single-dish surve...

show abstract

Section: Vinyl Cyanide C 2 H 3 Cnmentioning

confidence: 99%

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Беллоче

Müller

Menten

et al. 2013

A&A

375

523

View full text Add to dashboard Cite

show abstract

“…Transition frequencies in the range of our survey are mostly from that study. For the main species, they are, to a large extent, also from Baskakov et al (1996). Predictions for excited states of vinyl cyanide used in the present work are based on Cazzoli & Kisiel (1988) and unpublished data from one of us (HSPM).…”

Section: Spectroscopic Predictionsmentioning

confidence: 99%

Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)

Беллоче

Müller

Garrod

et al. 2016

A&A

190

345

View full text Add to dashboard Cite

Context. Deuteration is a powerful tracer of the history of the cold prestellar phase in star-forming regions. Apart from methanol, little is known about deuterium fractionation of complex organic molecules in the interstellar medium, especially in regions forming high-mass stars. Aims. Our goal is to detect deuterated complex organic molecules toward the high mass star-forming region Sagittarius B2 (Sgr B2) and derive the level of deuteration for these molecules. Methods. We use a complete 3-mm spectral line survey performed with the Atacama Large Millimeter/submillimeter Array (ALMA) to search for deuterated complex organic molecules toward the hot molecular core Sgr B2(N2). We constructed population diagrams and integrated intensity maps to fit rotational temperatures and emission sizes for each molecule. Column densities are derived by modeling the full spectrum under the assumption of local thermodynamic equilibrium. We compare the results to predictions of two astrochemical models that treat the deuteration process. Results. We report the detection of CH 2 DCN toward Sgr B2(N2) with a deuteration level of 0.4%, and tentative detections of CH 2 DOH, CH 2 DCH 2 CN, the chiral molecule CH 3 CHDCN, and DC 3 N with levels in the range 0.05%-0.12%. A stringent deuteration upper limit is obtained for CH 3 OD (<0.07%). Upper limits in the range 0.5-1.8% are derived for the three deuterated isotopologues of vinyl cyanide, the four deuterated species of ethanol, and CH 2 DOCHO. Ethyl cyanide is less deuterated than methyl cyanide by at least a factor five. The [CH 2 DOH]/[CH 3 OD] abundance ratio is higher than 1.8. It may still be consistent with the value obtained in Orion KL. Except for methyl cyanide, the measured deuteration levels lie at least a factor four below the predictions of current astrochemical models. The deuteration levels in Sgr B2(N2) are also lower than in Orion KL by a factor of a few up to a factor ten. Conclusions. The discrepancy between the deuteration levels of Sgr B2(N2) and the predictions of chemical models, and the difference between Sgr B2(N2) and Orion KL may both be due to the higher kinetic temperatures that characterize the Galactic center region compared to nearby clouds. Alternatively, they may result from a lower overall abundance of deuterium itself in the Galactic center region by up to a factor ten.

show abstract

“…1) were used. These entries are based on laboratory work by Gerry & Winnewisser (1973), Baskakov et al (1996), and Cazzoli & Kisiel (1988) for the main isotopic species and Colmont et al (1997) for the 13 C isotopologues. For CH 2 CHCN, most lines were optically thick and were not modeled, as previously discussed.…”

Section: Two Distinct Lines Of H Cs 2 13mentioning

confidence: 99%

The ¹²C/¹³C Ratio in Sgr B2(N): Constraints for Galactic Chemical Evolution and Isotopic Chemistry

Halfen

Woolf

Ziurys

2017

ApJ

View full text Add to dashboard Cite

A study has been conducted of 12 C/ 13 C ratios in five complex molecules in the Galactic center. H 2 CS, CH 3 CCH, NH 2 CHO, CH 2 CHCN, and CH 3 CH 2 CN and their 13 C-substituted species have been observed in numerous transitions at 1, 2, and 3 mm, acquired in a spectral-line survey of Sgr B2(N), conducted with the telescopes of the Arizona Radio Observatory (ARO). Between 22 and 54 individual, unblended lines for the 12 C species and 2-54 for 13 C-substituted analogs were modeled in a global radiative transfer analysis. All five molecules were found to consistently exhibit two velocity components near V LSR ∼ 64 and 73 km s −1 , with column densities ranging from N tot ∼ 3 × 10 14 −4 × 10 17 cm −2 and ∼2 × 10 13 −1 × 10 17 cm −2 for the 12 C and 13 C species, respectively. Based on 14 different isotopic combinations, ratios were obtained in the range 12 C/ 13 C = 15±5 to 33±13, with an average value of 24±7, based on comparison of column densities. These measurements better anchor the 12 C/ 13 C ratio at the Galactic center, and suggest a slightly revised isotope gradient of 12 C/ 13 C = 5.21(0.52) D GC + 22.6(3.3). As indicated by the column densities, no preferential 13 C enrichment was found on the differing carbon sites of CH 3 CCH, CH 2 CHCN, and CH 3 CH 2 CN. Because of the elevated temperatures in Sgr B2(N), 13 C isotopic substitution is effectively "scrambled," diminishing chemical fractionation effects. The resulting ratios thus reflect stellar nucleosynthesis and Galactic chemical evolution, as is likely the case for most warm clouds.

show abstract

Microwave Spectroscopy of Vinyl Cyanide, Taking into Account the Hyperfine Structure

Cited by 22 publications

References 0 publications

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)

The ¹²C/¹³C Ratio in Sgr B2(N): Constraints for Galactic Chemical Evolution and Isotopic Chemistry

Contact Info

Product

Resources

About

Microwave Spectroscopy of Vinyl Cyanide, Taking into Account the Hyperfine Structure

Cited by 22 publications

References 0 publications

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)

The 12C/13C Ratio in Sgr B2(N): Constraints for Galactic Chemical Evolution and Isotopic Chemistry

Contact Info

Product

Resources

About

The ¹²C/¹³C Ratio in Sgr B2(N): Constraints for Galactic Chemical Evolution and Isotopic Chemistry