Millimetre-wave spectrum of anti-13C1 and 13C2 isotopologues of ethanol

Bouchez, Aurelia; Walters, A.; Müller, H. S. P.; Ordu, Matthias H.; Lewen, Frank; Koerber, Monika; Bottinelli, S.; Endres, Christian

doi:10.1016/j.jqsrt.2012.02.025

Cited by 19 publications

(16 citation statements)

References 29 publications

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“…Additional data in the range of our survey were taken from Pearson et al (1995Pearson et al ( , 1996Pearson et al ( , 1997. We use the CDMS entries for the 13 C isotopologues (tags 47 511 and 47 512, both version 1) which are based on Bouchez et al (2012).…”

Section: Ethanol C 2 H 5 Ohmentioning

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

385

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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...

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Section: Ethanol C 2 H 5 Ohmentioning

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

385

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“…They were based on Bouchez et al (2012), which restricted the investigations to the anti conformers with J and K a ranges in which interaction with the gauche conformers can be neglected. The contribution of the gauche conformers to the partition function increases the value at 150 K based on the anti conformer only by a factor of ∼2.39 as estimated in the CDMS documentation from the main isotopic Takano et al (1968) and Kakar & Quade (1980) for anti and gauche conformers of ethanol, respectively.…”

Section: Ethanol C 2 H 5 Ohmentioning

confidence: 99%

“…This is very unusual for an asymmetric top rotor close to the prolate limit, which usually has a positive value. For example, ∼23 and ∼18 Hz were obtained for the anti conformers of the two isotopomers of ethanol with one 13 C (Bouchez et al 2012), ∼13.5 Hz for dimethyl ether with 0 (Endres et al 2009), 1, and 2 13 C atoms (Koerber et al 2013), and 93 Hz for propargyl alcohol (Pearson & Drouin 2005). Therefore, we suspect that there are errors in the quantum chemical calculations of sextic distortion parameters in Puzzarini et al (2014).…”

Section: Fig 2 Same As Inmentioning

confidence: 99%

Exploring molecular complexity with ALMA (EMoCA): Alkanethiols and alkanols in Sagittarius B2(N2)

Müller

Беллоче

et al. 2016

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Context. Over the past five decades, radio astronomy has shown that molecular complexity is a natural outcome of interstellar chemistry, in particular in star forming regions. However, the pathways that lead to the formation of complex molecules are not completely understood and the depth of chemical complexity has not been entirely revealed. In addition, the sulfur chemistry in the dense interstellar medium is not well understood. Aims. We want to know the relative abundances of alkanethiols and alkanols in the Galactic center source Sagittarius B2(N2), the northern hot molecular core in Sgr B2(N), whose relatively small line widths are favorable for studying the molecular complexity in space. Methods. We investigated spectroscopic parameter sets that were able to reproduce published laboratory rotational spectra of ethanethiol and studied effects that modify intensities in the predicted rotational spectrum of ethanol. We used the Atacama Large Millimeter Array (ALMA) in its Cycles 0 and 1 for a spectral line survey of Sagittarius B2(N) between 84 and 114.4 GHz. These data were analyzed by assuming local thermodynamic equilibrium (LTE) for each molecule. Our observations are supplemented by astrochemical modeling; a new network is used that includes reaction pathways for alkanethiols for the first time. Results. We detected methanol and ethanol in their parent 12 C species and their isotopologs with one 12 C atom substituted by 13 C; the latter were detected for the first time unambiguously in the case of ethanol. The 12 C/ 13 C ratio is ∼25 for both molecules. In addition, we identified CH OH ratio of ∼7.3. Upper limits were derived for the next larger alkanols normal-and iso-propanol. We observed methanethiol, CH 3 SH, also known as methyl mercaptan, including torsionally excited transitions for the first time. We also identified transitions of ethanethiol (or ethyl mercaptan), though not enough to claim a secure detection in this source. The ratios CH 3 SH to C 2 H 5 SH and C 2 H 5 OH to C 2 H 5 SH are 21 and 125, respectively. In the process of our study, we noted severe discrepancies in the intensities of observed and predicted ethanol transitions and propose a change in the relative signs of the dipole moment components. In addition, we determined alternative sets of spectroscopic parameters for ethanethiol. The astrochemical models indicate that substantial quantities of both CH 3 SH and C 2 H 5 SH may be produced on the surfaces of dust grains, to be later released into the gas phase. The modeled ratio CH 3 SH/C 2 H 5 SH = 3.1 is lower than the observed value of 21; the model value appears to be affected most by the underprediction of CH 3 SH relative to CH 3 OH and C 2 H 5 OH, as judged by a very high CH 3 OH/CH 3 SH ratio. Conclusions. The column density ratios involving methanol, ethanol, and methanethiol in Sgr B2(N2) are similar to values reported for Orion KL, but those involving ethanethiol are significantly different and suggest that the detection of ethanethiol reported toward Orion KL ...

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“…Several spectroscopic investigations were performed in support of this study, for example on iso-propyl cyanide (Müller et al 2011), anti-ethanol with one 13 C (Bouchez et al 2012), 2-aminopropionitrile (Møllendal et al 2012), and n-butyl cyanide (Ordu et al 2012). In addition, a number of spectroscopic studies have been prompted by the results of these line surveys, for example, on methyleneaminoacetonitrile (Motiyenko et al 2013), aminoacetonitrile (Motoki et al 2013), and 1,2-propanediol (Bossa et al 2014).…”

Section: Introductionmentioning

confidence: 62%

The millimeter and sub-millimeter rotational spectrum of triple ¹³C-substituted ethyl cyanide

Pienkina

Margulès

Motiyenko

et al. 2017

A&A

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Context.A recently published astronomical detection of all three doubly 13 C-substituted ethyl cyanides toward Sgr B2(N2) motivated us to investigate triple 13 C isotopic species that are expected to be also present in the ISM. Aims. We aim to present an experimental study of the rotational spectrum of triple 13 C-substituted ethyl cyanide, 13 CH 13 3 CH 13 2 CN, in the frequency range 150-990 GHz. We want to use the determined spectroscopic parameters for searching for 13 CH 13 3 CH 13 2 CN in ALMA data. The main objective of this work is to provide accurate frequency predictions to search for this molecule in the Galactic center source Sagittarius B2(N) and to facilitate its detection in space.Methods. The laboratory rotational spectrum of 13 CH 13 3 CH 13 2 CN has been recorded with the Lille's fast DDS solid-state spectrometer between 150 GHz and 990 GHz. Results. More than 4000 rotational transitions were identified in the laboratory. The quantum numbers reach J = 115 and K a = 39. Watson's Hamiltonian in the A and S reductions were used to analyze the spectra. Accurate spectroscopic parameters were determined. The rotational spectra of the 13 C containing species CH 3 CH 2 CN have been assigned, thus allowing the determination of the rotational and centrifugal distortion constants

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Millimetre-wave spectrum of anti-13C1 and 13C2 isotopologues of ethanol

Cited by 19 publications

References 29 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): Alkanethiols and alkanols in Sagittarius B2(N2)

The millimeter and sub-millimeter rotational spectrum of triple ¹³C-substituted ethyl cyanide

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Millimetre-wave spectrum of anti-13C1 and 13C2 isotopologues of ethanol

Cited by 19 publications

References 29 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): Alkanethiols and alkanols in Sagittarius B2(N2)

The millimeter and sub-millimeter rotational spectrum of triple 13C-substituted ethyl cyanide

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The millimeter and sub-millimeter rotational spectrum of triple ¹³C-substituted ethyl cyanide