J/A+A/vol/page Rotational spectroscopy of methyl mercaptan (Zakharenko+, 2019) ================================================================================ Rotational spectroscopy of methyl mercaptan CH_{3}^{32}SH at millimeter and submillimeter wavelengths O. Zakharenko, V. Ilyushin, F. Lewen, et al. =2019A&A...VVV.ppppI (SIMBAD/NED BibCode) ================================================================================ Keywords: Methods: laboratory: molecular -- Techniques: spectroscopic -- ISM: molecules -- Astrochemistry Abstract: We present a new global study of the millimeter wave, submillimeter wave, and THz spectra of the lowest three torsional states of methyl mercaptan (CH3SH). New measurements have been carried out between 50 and 510 GHz using the Kharkiv mm wave and the Cologne submm wave spectrometers whereas THz spectra records were used from our previous study. The new data involving torsion-rotation transitions with J up to 61 and Ka up to 18 were combined with previously published measurements and fitted using the rho-axis-method torsion-rotation Hamiltonian. The final fit used 124 parameters to give an overall weighted root- mean-square deviation of 0.72 for the dataset consisting of 6965 microwave and 16345 FIR line frequencies sampling transitions within and between the ground, first, and second excited torsional states of the molecule. This investigation presents a twofold expansion in the J quantum numbers and a significant improvement in the fit quality, especially for the microwave part of the data thus allowing us to provide improved predictions to support astronomical observations. Description: FTFIRdata.txt contains FTFIR data used in the current fit of methyl mercaptan spectrum. MWdata.txt contains microwave data used in the current fit of methyl mercaptan spectrum. Predict.txt contains calculated spectrum of methyl mercaptan main isotopolog for the ground, first, and second excited torsional states in the range 1 - 2000 GHz. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- readme.txt 80 . This file FTFIRdata.txt 68 19466 FTFIR data used in the current fit of methyl mercaptan spectrum. MWdata.txt 75 7813 Microwave data used in the current fit of methyl mercaptan spectrum. Predict.txt 82 39067 Predicted transitions of the vt=0,1,2 torsional states of methyl mercaptan in 1 - 2000 GHz range. -------------------------------------------------------------------------------- Byte-by-byte Description of file: FTFIRdata.txt -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 2 A2 --- Sym' Upper level symmetry species in G6 3- 5 I3 --- m' Upper free rotor m quantum number 6- 9 I4 --- J' Upper J quantum number 10- 13 I4 --- Ka' Upper Ka quantum number 14- 17 I4 --- Kc' Upper Kc quantum number 22- 23 A2 --- Sym" Lower level symmetry species in G6 24- 26 I3 --- m" Lower free rotor m quantum number 27- 30 I4 --- J" Lower J quantum number 31- 34 I4 --- Ka" Lower Ka quantum number 35- 38 I4 --- Kc" Lower Kc quantum number 39- 49 F11.5 cm-1 Freq Measured transition frequency 50- 58 F9.5 cm-1 Unc Measurement uncertainty of transition frequency 59- 68 F9.5 cm-1 O-C Obs.-cal. difference in the fit -------------------------------------------------------------------------------- Byte-by-byte Description of file: MWdata.txt -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 2 A2 --- Sym' Upper level symmetry species in G6 3- 5 I3 --- m' Upper free rotor m quantum number 6- 9 I4 --- J' Upper J quantum number 10- 13 I4 --- Ka' Upper Ka quantum number 14- 17 I4 --- Kc' Upper Kc quantum number 22- 23 A2 --- Sym" Lower level symmetry species in G6 24- 26 I3 --- m" Lower free rotor m quantum number 27- 30 I4 --- J" Lower J quantum number 31- 34 I4 --- Ka" Lower Ka quantum number 35- 38 I4 --- Kc" Lower Kc quantum number 39- 51 F12.3 MHz Freq Measured transition frequency 52- 59 F8.3 MHz Unc Measurement uncertainty of transition frequency 60- 69 F10.3 MHz O-C Obs.-cal. difference in the fit 70- 75 A6 --- Com Source of the data (1) -------------------------------------------------------------------------------- Note (1): Blank space - current work, letter coding from Xu et al. (2012): Asterisks mark those lines which were excluded from the fit in Xu et al. (2012). Xu, L.-H., Lees, R. M., Crabbe, G. T., et al. 2012, J. Chem. Phys., 137, 104313. Byte-by-byte Description of file: Predict.txt -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 2 A2 --- Sym' Upper level symmetry species in G6 3- 5 I3 --- m' Upper free rotor m quantum number 6- 9 I4 --- J' Upper J quantum number 10- 13 I4 --- Ka' Upper Ka quantum number 14- 17 I4 --- Kc' Upper Kc quantum number 22- 23 A2 --- Sym" Lower level symmetry species in G6 24- 26 I3 --- m" Lower free rotor m quantum number 27- 30 I4 --- J" Lower J quantum number 31- 34 I4 --- Ka" Lower Ka quantum number 35- 38 I4 --- Kc" Lower Kc quantum number 39- 52 F14.4 MHz Freq Predicted transition frequency 53- 60 F8.4 MHz Unc Predicted uncertainty of transition frequency 61- 72 F12.4 cm-1 Elow The energy of the lower state 73- 82 F10.3 D^2 mu2S Linestrength multiplied by dipole moment squared -------------------------------------------------------------------------------- ================================================================================ (End) Holger S.P. Muller [U Cologne] 23-Apr-2019