J/A+A/552/A117 Mono-deuterated dimethyl ether (Richard+, 2013)
Mono-deuterated dimethyl ether: laboratory spectrum up to 1 THz.
Torsion-rotational spectrum within the vibrational ground-state for the
symmetric and asymmetric conformers and first detection in IRAS16293-2422.
Richard C., Margules L., Caux E., Kahane C., Ceccarelli C., Guillemin J.C.,
Motiyenko R.A., Vastel C., Groner P.
<Astron. Astrophys. 552, A117 (2013)>
=2013A&A...552A.117R 2013A&A...552A.117R
ADC_Keywords: Atomic physics
Keywords: line: identification - method: laboratory - molecular data -
techniques: spectroscopic - submillimeter: ISM - ISM: molecules
Abstract:
Dimethyl ether is one of the most abundant complex organic molecules
(COMs) in star-forming regions. Like other COMs, its formation process
is not yet clearly established, but the relative abundances of its
deuterated isotopomers may provide crucial hints in studying its
chemistry and tracing the source history. The mono-deuterated species
(CH2DOCH3) is still a relatively light molecule compared to other
COMs. Its spectrum is the most intense in the THz domain in the
100-150K temperature regime, tracing the inner parts of the low-mass
star-forming region. Therefore, it is necessary to measure and assign
its transitions in this range in order to be able to compute accurate
predictions required by astronomical observations, in particular with
the telescope operating in the submm range, such as ALMA. We present
the analysis of mono-deuterated dimethyl ether in its
ground-vibrational state, based on an effective Hamiltonian for an
asymmetric rotor molecules with internal rotors, The analysis covers
the frequency range 150-990GHz. The laboratory rotational spectrum
of this species was measured with a submillimeter spectrometer
(50-990GHz) using solid-state sources. For the astronomical
detection, we used the IRAM 30m telescope to observe a total range of
27GHz, in 4 frequency bands from 100GHz to 219GHz.
New sets of spectroscopic parameters have been determined by a least
squares fit with the ERHAM code for both conformers. These parameters
have permitted the first identification in space of both
mono-deuterated DME isomers via detection of twenty transitions in the
solar-type protostar IRAS16293-2422 with the IRAM 30m telescope. The
DME deuteration ratio in this source appears as high as observed for
methanol and formaldehyde, two species known to play an important role
in the COMs formation history.
Description:
The tables present the experimental frequencies of rotational
transitions for the symmetric and asymmetric conformers of
mono-deuterated dimethylether up to 1THz and the predicted
frequencies up to 1.2THz.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 66 1777 *Measured transitions of symmetric DME-1d
tablea2.dat 66 2123 *Measured transitions of asymmetric DME-1d
tableb1.dat 77 7314 Predicted transitions of symmetric DME-1d
tableb2.dat 77 8242 Predicted transitions of asymmetric DME-1d
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Note on tablea1.dat, tablea2.dat: the mono-deuterated DimEthyl Ether
(CDH2-O-CH3) is symmetric when the D atom is in the C-O-C plane,
and asymmetric otherwise.
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See also:
J/A+A/543/A135 : New analysis of 13C-CH3CH2CN up to 1THz (Richard+, 2012)
Byte-by-byte Description of file: tablea1.dat tablea2.dat
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Bytes Format Units Label Explanations
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1 I1 --- sig [0/1] Symmetry number σ: 0(A), 1(E)
5- 6 I2 --- J0 [0/55] J value of the lower state
10- 11 I2 --- Ka0 [0/19] Ka value of the lower state
15- 16 I2 --- Kc0 [0/55] Kc value of the lower state
20- 21 I2 --- J1 [0/54] J value of the upper state
25- 26 I2 --- Ka1 [0/18] Ka value of the upper state
30- 31 I2 --- Kc1 [0/54] Kc value of the upper state
35- 45 F11.4 MHz Freq Measured frequency
50- 55 F6.4 MHz Acc Accuracy of the measure (1)
58- 66 F9.4 MHz O-C Observed-calculated frequency
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Note (1): When accuracy is equal to 0.000, the line were excluded from the fit.
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Byte-by-byte Description of file: tableb1.dat tableb2.dat
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Bytes Format Units Label Explanations
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1 I1 --- sig [0/1] Symmetry number σ: 0(A), 1(E)
5- 6 I2 --- J0 [1/60] J value of the lower state
10- 11 I2 --- Ka0 [0/24] Ka value of the lower state
15- 16 I2 --- Kc0 [0/60] Kc value of the lower state
20- 21 I2 --- J1 [0/59] J value of the upper state
25- 26 I2 --- Ka1 [0/23] Ka value of the upper state
30- 31 I2 --- Kc1 [0/60] Kc value of the upper state
34- 44 F11.3 MHz Freq Predicted frequency
49- 53 F5.3 MHz e_Freq Uncertainty of the prediction
57 I1 --- Spin [4] Spin weight
61- 67 F7.4 --- S Line strength for the dipole µb component
70- 77 F8.3 cm-1 E' Value of the upper energy level
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Acknowledgements:
Cyril Richard, cyril.richard(at)phlam.univ-lille1.fr
Laurent Margules, laurent.margules(at)univ-lille1.fr
(End) Cyril Richard [PhLAM - Lille], Patricia Vannier [CDS] 10-Apr-2013