J/A+A/686/L3 Predicted frequencies for NCCHCS (Cabezas+, 2024)
Laboratory and astronomical discovery of cyanothioketene, NCCHCS, in the cold
starless core TMC-1.
Cabezas C., Agundez M., Endo Y., Tercero B., Lee Y.-P., Marcelino N.,
de Vicente P., Cernicharo J.
<Astron. Astrophys. 686, L3 (2024)>
=2024A&A...686L...3C 2024A&A...686L...3C (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics
Keywords: astrochemistry - line: identification - molecular data -
methods: laboratory: molecular - ISM: molecules -
ISM: individual objects: TMC-1
Abstract:
We present the detection of cyanothioketene, NCCHCS, in the laboratory
and toward TMC-1. This transient species was produced through a
discharge of a gas mixture of CH2CHCN and CS2 using argon as
carrier gas, and its rotational spectrum between 9 and 40GHz was
characterized using a Balle-Flygare narrowband-type Fourier-transform
microwave spectrometer. A total of 21 rotational transitions were
detected in the laboratory, all of them exhibiting hyperfine structure
induced by the spin of the N nucleus. The spectrum for NCCHCS was
predicted in the domain of our line surveys using the derived
rotational and distortion constants. The detection in the cold
starless core TMC-1 was based on the QUIJOTE line survey performed
with the Yebes 40m radio telescope. Twenty-three lines were detected
with Ka=0, 1, and 2 and Ju=9 up to 14. The derived column density is
(1.2±0.1)1011cm-2 for a rotational temperature of 8.5±1K. The
abundance ratio of thioketene and its cyano derivative,
H2CCS/NCCHCS, is 6.5±1.3. Although ketene is more abundant than
thioketene by about 15 times, its cyano derivative NCCHCO surprisingly
is not detected with a 3sigma upper level to the column density of
3.0x1010cm-2, which results in an abundance ratio
H2CCO/NCCHCO>430. Hence, the chemistry of CN derivatives seems to be
more favored for S-bearing than for O-bearing molecules. We carried
out chemical modeling calculations and found that the gas-phase
neutral-neutral reactions CC+H2CS and CN+H2CCS could be a source
of NCCHCS in TMC-1.
Description:
Table A2 contains the predicted rotational transitions frequencies up
to 300GHz for NCCHCS molecule.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea2.dat 75 17339 Predicted frequencies for NCCHCS
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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3- 13 F11.4 MHz Freq Frequency
16- 21 F6.4 MHz e_Freq Frequency uncertainty
22- 29 F8.4 [nm2.MHz] logInt Base 10 logarithm of the integrated intensity
31 I1 cm-1 DR Degrees of freedom of rotation partition
function
33- 41 F9.4 cm-1 Elow Lower state energy
42- 44 I3 cm-1 Gup Upper state degeneracy
47- 51 I5 --- TAG Molecular identifier
53- 55 I3 --- QNFMT Quantum numbers code
56- 57 I2 --- J' Quantum number J for upper level
58- 59 I2 --- Ka' Quantum number Ka for upper level
60- 61 I2 --- Kc' Quantum number Kc for upper level
62- 63 I2 --- F' Quantum number F for upper level
68- 69 I2 --- J" Quantum number N for lower level
70- 71 I2 --- Ka" Quantum number Ka for lower level
72- 73 I2 --- Kc" Quantum number Kc for lower level
74- 75 I2 --- F" Quantum number F for lower level
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Acknowledgements:
Carlos Cabezas, carlos.cabezas(at)csic.es
(End) Patricia Vannier [CDS] 06-May-2024