Dimethyl ether: laboratory spectra up to 2.1 THz

Endres, Christian; Drouin, Brian J.; Pearson, John C.; Müller, H. S. P.; Lewen, Frank; Schlemmer, S.; Giesen, Thomas

doi:10.1051/0004-6361/200912409

Cited by 59 publications

(49 citation statements)

References 22 publications

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“…It is based on the very extensive analysis of Endres et al (2009) and employed additional rest frequencies in the range of our survey from Lovas et al (1979) and Neustock et al (1990). The entries for the vibrationally excited states 11 = 1 and 15 = 1 were provided by C. Endres.…”

Section: Dimethyl Ether Ch 3 Ochmentioning

confidence: 99%

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

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Müller

Menten

et al. 2013

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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: Dimethyl Ether Ch 3 Ochmentioning

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

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523

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“…The intensities are presented relative to the strongest band of each isotopologue. In general, there is a good agreement between calculated and observed band positions for all isotopologues, especially for DME-d 3 .…”

Section: • Results and Discussionmentioning

confidence: 52%

“…Once a new PES is obtained after replacing a by a', a single coefficient is also shifted for each isotopologue, B on for DMEd 6 and A 010 (keeping A 010 = A 001 for the potential term V) for DME-d 3 , to obtain very accurate torsional energies. Thus, the definitive adjusted PES (V ADJ ) reproduces accurately both bending and torsional frequencies.…”

Section: • Results and Discussionmentioning

confidence: 99%

“…The aim of the present paper is the study of two deuterated isotopologues DME-d 6 and DME-d 3 . DME-d 6 can be classified in the G 36 molecular symmetry group (MSG), such as the most abundant species DME-/z 6 …”

Section: ^3d -~2j 2jmentioning

confidence: 99%

“…In the present paper, we analyze two DME isotopologues containing deuterium, 12 CD 3 -16 0-12 CD 3 (DME-d 6 ) and 12 CH 3 -16 0-12 CD 3 (DME-d 3 ), of which far-infrared and microwave spectra were recorded by Groner and Durig in the 1970s. 5 ' 14 Here, we review the former spectral assignments from a different point of view, the one provided by accurate ab initio calculations.…”

Section: • Introductionmentioning

confidence: 99%

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CCSD(T) Study of CD₃–O–CD₃ and CH₃–O–CD₃ Far-Infrared Spectra

et al. 2012

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From a vibrationally corrected 3D potential energy surface determined with highly correlated ab initio calculations (CCSD(T)), the lowest vibrational energies of two dimethyl-ether isotopologues, 12 CH 3 -16 0-12 CD 3 (DMEd 3 ) and 12 CD 3 -16 0-12 CD 3 (DME-d 6 ), are computed variationally. The levels that can be populated at very low temperatures correspond to the COC-bending and the two methyl torsional modes. Molecular symmetry groups are used for the classification of levels and torsional splittings. DME-d 6 belongs to the G 36 group, as the most abundant isotopologue 12 CH 3 -16 0-12 CH 3 (DME-iiJ, while DME-A, is a G 18 species. Previous assignments of experimental Raman and far-infrared spectra are discussed from an effective Hamiltonian obtained after refining the ab initio parameters. Because a good agreement between calculated and experimental transition frequencies is reached, new assignments are proposed for various combination bands corresponding to the two deuterated isotopologues and for the 020 ->• 030 transition of DME-d 6 . Vibrationally corrected potential energy barriers, structural parameters, and anharmonic spectroscopic parameters are provided. For the 3N -9 neglected vibrational modes, harmonic and anharmonic fundamental frequencies are obtained using second-order perturbation theory by means of CCSD and MP2 force fields. Fermi resonances between the COC-bending and the torsional modes modify DME-d 3 intensities and the band positions of the torsional overtones.

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