J/A+A/644/A102 CH3SC(O)H observed line frequencies and strengths (Jabri+, 2020)
Rotational spectroscopic study of S-methyl thioformate: A global laboratory
analysis of ground and excited torsional states up to 660 GHz.
Jabri A., Tercero B., Margules L., Motiyenko R.A., Alekseev E.A.,
Kleiner I., Cernicharo J., Guillemin J.-C.
<Astron. Astrophys. 644, A102 (2020)>
=2020A&A...644A.102J 2020A&A...644A.102J (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Radio sources ; Abundances ; Atomic physics
Keywords: line identification - catalogs - ISM: abundances -
submillimeter: ISM - methods: laboratory: molecular
Abstract:
S-methyl thioformate CH3SC(O)H is a monosulfur derivative of methyl
formate, a relatively abundant component of the interstellar medium
(ISM).
S-methyl thioformate being, thermodynamically,the most stable isomer,
it can be reasonably proposed for detection in the ISM. This work aims
to experimentally study and theoretically analyze the ground and first
torsional excited states for CH3SC(O)H in a large spectral range for
astrophysical use. S-methyl thioformate was synthesized as a result of
a reaction of methyl mercaptan with acetic-formic anhydride.
The millimeter-wave spectrum was then recorded for the first time from
150 to 660GHz with the solid-state-based spectrometer at Lille.
A set of 3545 lines is determined and combined with 54 previously
measured lines in the microwave region, belonging to ground state vt=0
as well as 1391 transitions in the first excited state of torsion
v18=1. Some 164 lines were also assigned to vt18=2 for the A-species.
A global fit was performed using the BELGI-Cs code taking into account
the large splitting of A and E lines due to methyl internal rotation
motion with a relatively low barrier, V3=127.4846(15)cm-1. Using
our spectroscopy work, a deep search of S-methyl thioformate was
carried out in the IRAM 30m and ALMA data of different high-mass
star-forming regions (Orion KL and Sgr B2). We derived an upper limit
to the CH3SC(O)H column density in these regions.
Description:
TableA1 shows the laboratory observed line frequencies (with their
experimental uncertainties under parentheses), calculated frequencies,
observed-calculated frequencies, line strengths (S.µ2), upper
state and lower state energies, as well as the assignments for the
observed transitions of methyl thioformate CH3SC(O)H in the
millimeter wave and submillimeter wave spectral ranges. All the
observed transitions of Table A.1 were included in the fitting
BELGI-Cs code (see also Kleiner, 2010, J. Mol. Spectrosc., 260, 1). No
statistical weights are included in this table.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 124 5154 Observed line frequencies and line strengths
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- vt' Upper state torsional quantum number
7- 8 I2 --- J' Upper state rotational quantum number
10- 12 I3 --- Ka' Upper state projection of J on the
a-principal axis
15- 16 I2 --- Kc' Upper state projection of J on the
c-principal axis
18 A1 --- P' Upper state "parity" quantum number for
A species
19- 22 I4 --- vt" lower state torsional quantum number
25- 26 I2 --- J" lower state rotational quantum number
28- 30 I3 --- Ka" Lower state projection of J on the
a-principal axis
33- 34 I2 --- Kc" Lower state projection of J on the
c-principal axis
36 A1 --- P" Lower state "parity" quantum number for
A species
40 A1 --- Symmetry Symmetry species (A or E) for the internal
rotor
45- 55 F11.3 MHz Obs Observed transition frequency in the
laboratory
56 A1 --- --- [(]
57- 59 I3 kHz Unc Experimental uncertainty
60 A1 --- --- [)]
63- 73 F11.3 MHz Calc Calculated frequency
81- 87 F7.3 MHz Obs-Calc Observed-Calculated residuals
90- 99 F10.4 cm-1 Eup Upper state energy
100-109 F10.4 cm-1 Elow Lower state energy
113-124 E12.6 D+2 Smu2 Line Strength (in Debye2 unit)
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Acknowledgements:
Isabelle Kleiner, isabelle.kleiner(at)lisa.ipsl.fr
(End) Patricia Vannier [CDS] 19-Nov-2020