J/A+A/627/A41 CH3(34)SH laboratory spectroscopic study (Zakharenko+, 2019)
Rotational spectroscopy of isotopic species of methyl mercaptan at millimeter
and submillimeter wavelengths: CH3(34)SH.
Zakharenko O., Lewen F., Ilyushin V.V., Mueller H.S.P., Schlemmer S.,
Alekseev A.A., Krapivin I., Xu L.-H., Lees R.M., Garrod R., Belloche A.,
Menten K.M.
<Astron. Astrophys. 627, A41 (2019)>
=2019A&A...627A..41Z 2019A&A...627A..41Z (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics ; Models
Keywords: methods: laboratory: molecular - techniques: spectroscopic -
ISM: molecules - astrochemistry - ISM: abundances - radio lines: ISM
Abstract:
Methyl mercaptan (CH3SH) is an important sulfur-bearing species in
the interstellar medium, terrestrial environment, and potentially in
planetary atmospheres. The aim of the present study is to provide
accurate spectroscopic parameters for the most abundant minor
isotopolog CH334SH to support radio astronomical observations at
millimeter and submillimeter wavelengths. The rotational spectrum of
CH3(34)SH, which is complicated by the large-amplitude internal
rotation of the CH3 group versus the 34SH frame, was investigated
in the 49-510GHz and 1.1-1.5THz frequency ranges in natural isotopic
abundance. The analysis of the spectrum was performed up to the second
excited torsional state, and the obtained data were modeled with the
RAM36 program. A fit within experimental accuracy was obtained with a
RAM Hamiltonian model that uses 72 parameters. Predictions based on
this fit are used to search for CH334SH with the Atacama Large
Millimeter/submillimeter Array (ALMA) toward the hot molecular core
Sgr B2(N2), but blends with emission lines of other species prevent
its firm identification in this source.
Description:
Measurements in Cologne were done in the frequency ranges of
155-510GHz and 1.1-1.5THz using the Cologne mm/submm wave and THz
spectrometers.
Input and output files.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
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ReadMe 80 . Thsi file
input_34S.txt 153 3610 input text file for the program RAM36
output_34S.txt 192 14024 output text file from the program RAM36
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Description of file:
input_34S.txt
The first 4 lines contain information about the operating mode of the
program. The next 6 lines remind the user of the format of the
Hamiltonian parameters. Then the list of parameters used in the fit is
given. The line &&&END,,,,,,,,, signals the end of this list. The
parameter values are given in cm-1. Each line with a Hamiltonian
parameter contains the parameter name, a set of 7 integers that define
the associated quantum mechanical operator, a value for the parameter
(i.e., for the coefficient of this operator), the diagonalization
stage in which the particular parameter is used, and a float/fix flag.
The actual term is encoded by the set of 7 integers, which are
the powers of operators from the Hamiltonian expression. Thus:
k - (the first integer) corresponds to the power of J**2,
n - (the second integer) corresponds to the power of Jz,
p,q - are powers of Jx, Jy,
r - is the power of pa,
s - (the sixth integer) defines the argument of cos(3sa),
t - (the seventh integer) defines the argument of sin(3ta).
The next 7 lines contain the information necessary for the fitting
process and the predictions calculation.
Then the list of measured transition frequencies is given.
First a measured frequency is given. Then the assignment quantum numbers
are given. They are followed by the include/exclude switch 'ifit' and
by the measurement uncertainty. After that space for a comment is
reserved.
The assignment consists of m, J, Ka, Kc quantum numbers. First the
upper level is given then the lower level is given. The labelling
procedure in the program determines from the eigenvector composition
the levels which belong to each particular m-state and then assigns
Ka,Kc labels within each m state according to the usual asymmetric
top energy ordering scheme.
output_34S.txt
The output file is organized as follows. First the initial values of
parameters as well as different statistics on the experimental data
(number of transitions, number of blended transitions, number of
levels included in the fit etc.) are given. Then, for each iteration,
the information on the parameter changes and current rms deviation for
different groups of data are given. Then the list of the parameter
values for the next iteration is presented in the format suitable for
the input file (so it can be copied and pasted easily to the input
file).
When the fit has converged or the maximum allowed number of iterations
has passed the output of obtained results is given. The list of
transitions with J<Jmax from the input file is given three times.
First it is given in order of frequency, second it is given in the
order it appears in the input file, and third it is given sorted by
spectroscopic branches. In these lists the assignments of the levels
are augmented by the symmetry species labels from the G12 group (for
V6) or from the G6 group (for V3). When the list of transitions is
presented sorted by branch the expectation value of the (23)*
operation is given and also if the transition is blended you will find
in the end of the line the letter 'b' with the residual calculated
from the special treatment of blends.
Detailled explanations on RAM36 could be found at
http://www.ifpan.edu.pl/~kisiel/introt/ram36/readmeram36.pdf
Xu, L.-H., Lees, R. M., Crabbe, G. T., et al. 2012, The Journal of Chemical
Physics, 137, 104313.
Tsunekawa, S., Taniguchi, I., Tambo, A., et al. 1989a, Journal of Molecular
Spectroscopy, 134, 63.
Endres C.P., Schlemmer S., Schilke P., Stutzki J. and Mueller H.S.P.,
The Cologne Database for Molecular Spectroscopy, CDMS, in the Virtual
Atomic and Molecular Data Centre, VAMDC,
J. Mol. Spectrosc. 327, 95-104 (2016).
Mueller H.S.P., Schloeder F., Stutzki J. and Winnewisser G.,
The Cologne Database for Molecular Spectroscopy, CDMS: a Useful Tool for
Astronomers and Spectroscopists, J. Mol. Struct. 742, 215-227 (2005).
Mueller H.S.P., Thorwirth S., Roth D.A. and Winnewisser G.,
The Cologne Database for Molecular Spectroscopy Astron. Astrophys. 370,
L49-L52 (2001).
Ilyushin, V. V., Endres, C. P., Lewen, F., Schlemmer, S., Drouin, B. J.
2013, Journal of Molecular Spectroscopy, 290, 31.
Ilyushin, V. V., Kisiel, Z., Pszczokowski, L., Maeder, H., Hougen, J. T.
2010, Journal of Molecular Spectroscopy, 259, 26.
Smirnov, I. A., Alekseev, E. A., Ilyushin, V. V., et al. 2014,
Journal of Molecular Spectroscopy, 295, 44.
For further data associated with the CH3(34)SH fits
https://cdms.astro.uni-koeln.de/classic/predictions/daten/Methanethiol/
Acknowledgements:
Holger S. P. Mueller, hspm(at)ph1.uni-koeln.de
(End) Patricia Vannier [CDS] 20-Jun-2019