J/A+A/616/A173 Rotational spectrum of ethyl isocyanate (Kolesnikova+, 2018)
Millimeter wave spectra of ethyl isocyanate and searches for it in Orion KL
and Sagittarius B2.
Kolesnikova L., Alonso E.R., Tercero B., Cernicharo J., Alonso J.L.
<Astron. Astrophys. 616, A173 (2018)>
=2018A&A...616A.173K 2018A&A...616A.173K (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Spectroscopy
Keywords: astrochemistry - ISM: molecules -
astronomical databases: miscellaneous -
ISM: individual objects: Orion KL - ISM: individual objects: Sgr B2
Abstract:
Relatively high abundances of methyl isocyanate (CH3NCO), a methyl
derivative of isocyanic acid (HNCO), found in the Orion KL and Sgr B2
molecular clouds suggest that its ethyl derivative, ethyl isocyanate
(CH3CH2NCO), may also be present.
The aim of this work is to provide accurate experimental frequencies
of ethyl isocyanate in its ground and excited vibrational states in
the millimeter wave region to support searches for it in the
interstellar medium.
The rotational spectrum of ethyl isocyanate was recorded at room
temperature from 80 to 340GHz using the millimeter wave spectrometer
in Valladolid. Assigned rotational transitions were analyzed using the
S-reduced semirigid-rotor Hamiltonian.
More than 1100 distinct frequency lines were analyzed for the ground
vibrational state of the cis conformer as well as for three
vibrational satellites corresponding to successive excitation of the
lowest-energy C-N torsional mode. Newly determined rotational and
centrifugal distortion constants were used for searches of spectral
features of ethyl isocyanate in Orion KL and Sgr B2 clouds. Upper
limits to CH3CH2NCO in these high-mass star-forming regions were
obtained.
Description:
Observed rotational transitions of ethyl isocyanate in the ground
state and excited vibrational states.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 111 1068 Fitted rotational transitions of ethyl isocyanate
in the ground state and excited vibrational states
table5.dat 50 394 Perturbed rotational transitions of ethyl isocyanate
in the ground vibrational state measured by the
graphical Loomis-Wood type plot technique
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See also:
J/A+A/610/A44 : Ethyl isocyanide submillimeter wave spectroscopy
(Margules+, 2018)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- J1 Upper state J quantum number
4- 6 I3 --- Ka1 Upper state Ka quantum number
7- 9 I3 --- Kc1 Upper state Kc quantum number
10- 12 I3 --- J0 Lower state J quantum number
13- 15 I3 --- Ka0 Lower state Ka quantum number
16- 18 I3 --- Kc0 Lower state Kc quantum number
23- 33 F11.4 MHz Freqobs Observed transition frequency
36- 42 F7.4 MHz O-C Observed minus calculated frequency
45- 50 F6.4 MHz Unc Experimental uncertainty
53- 59 F7.4 MHz (O-C)b ? Observed minus calculated frequency
for blends
61- 64 F4.2 --- wb ? Weight of the components of the blends
68-111 A44 --- Notes Notes
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- J1 Upper state J quantum number
4- 6 I3 --- Ka1 Upper state Ka quantum number
7- 9 I3 --- Kc1 Upper state Kc quantum number
10- 12 I3 --- J0 Lower state J quantum number
13- 15 I3 --- Ka0 Lower state Ka quantum number
16- 18 I3 --- Kc0 Lower state Kc quantum number
23- 33 F11.4 MHz Freqobs Observed transition frequency
45- 50 F6.4 MHz Unc Experimental uncertainty
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Acknowledgements:
Lucie Kolesnikova, lucie.kolesnikova(at)uva.es
(End) Lucie Kolesnikova [GEM, UVa, Spain], Patricia Vannier [CDS] 08-Jun-2018