J/A+A/621/A114 Deuterated methyl mercaptan (CH_3_SD) (Zakharenko+, 2019) ================================================================================ Deuterated methyl mercaptan (CH_3_SD): Laboratory rotational spectroscopy and search toward IRAS 16293-2422 B. Zakharenko O., Lewen F., Ilyushin V.V., Drozdovskaya M.N., Jorgensen J.K., Schlemmer S., Mueller H.S.P. =2019A&A...621A.114Z (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 (also known as methanethiol), CH_3_SH, has been found in the warm and dense parts of high- as well as low- mass star-forming regions. The aim of the present study is to obtain accurate spectroscopic parameters of the S-deuterated methyl mercaptan CH_3_SD to facilitate astronomical observations by radio telescope arrays at (sub)millimeter wavelengths. The rotational spectrum associated with the large-amplitude internal rotation of the methyl group of methyl mercaptan using an isotopically enriched sample has been measured in the 150-510GHz frequency range using the Koeln millimeter wave spectrometer. The analysis of the spectra has been performed up to the second excited torsional state. The results of the modeling of these data with the RAM36 program are presented. CH_3_SD was searched for, but not detected, in data from the Atacama Large Millimeter/submillimeter Array (ALMA) Protostellar Interferometric Line Survey (PILS) of the deeply embedded protostar IRAS 16293-2422. The derived upper limit corresponds to a degree of deuteration of at most ~18%. Description: input and output files. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file input.txt 153 5044 .txt input file for the program RAM36 output_CH3SD 191 19114 output file for CH_3_SD -------------------------------------------------------------------------------- Description of file: input.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_CH3SD 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