J/A+A/610/A44 Ethyl isocyanide submillimeter wave spectroscopy (Margules+, 2018) ================================================================================ Submillimeter wave spectroscopy of ethyl isocyanide and its searches in Orion. Margules L., Tercero B., Guillemin J.C., Motiyenko R.A., Cernicharo J. =2018A&A...610A..44M (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Atomic physics Keywords: ISM: molecules - methods: laboratory: molecular - submillimeter: ISM - molecular data - line: identification Abstract: About 40 cyanide molecules have been detected in the interstellar medium, but only 3 examples of organic isocyanide molecules were observed in this medium. Ethyl isocyanide is one of the best candidates for possible detection. To date, measurements of rotational spectra are limited to 40 GHz. The extrapolation of the prediction in the millimeter wave domain is inaccurate and does not permit an unambiguous detection. The rotational spectra were reinvestigated from 0.15 to 1THz. Using the new prediction, we searched for the compound ethyl isocyanide in Orion KL and Sgr B2. We newly assigned 2906 transitions and fitted these new data with those from previous studies, reaching quantum numbers up to J=103 and Ka=30. The asymmetric top Hamiltonian proposed by Watson in the Ir representation was used for the analysis, and both reductions A and S were tested. The search for CH_3_CH_2_NC in SgrB2 (IRAM 30m) and Orion KL (IRAM 30m, ALMA Science Verification) result in a non-detection; upper limits to the column density were derived. Description: Measured frequencies and residuals from the global fit of the submillimeter-wave data for ethylisocyanide and files used for SPFIT. Detailled explanations on SPFIT could be found at https://www.astro.uni-koeln.de/cdms/pickett File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file s1.dat 74 4462 Measured frequencies and residuals from the fit s2.lin 72 4462 .lin file, input file for SPFIT s3.par 80 26 .par file, input file for SPFIT s4.cat 73 17585 .cat prediction up to 990 GHz -------------------------------------------------------------------------------- See also: J/A+A/493/565 : Deuterated and ^15^N ethyl cyanides (Margules+, 2009) J/A+A/500/1109 : Rotational spectrum of HCOO^13^CH_3_ (Carvajal+, 2009) J/A+A/538/A51 : Rotational spectrum of CH_3_CH(NH_2_)CN (Mollendal+, 2012) J/A+A/538/A119 : Spectrum of ^18^O-methyl formate HCO^18^OCH_3_ (Tercero+ 2012) J/A+A/540/A51 : Submm spectrum of deuterated glycolaldehydes (Bouchez+, 2012) J/A+A/543/A46 : Submillimeter spectrum of HCOOCD_2_H (Coudert+, 2012) J/A+A/543/A135 : New analysis of ^13^C-CH_3_CH_2_CN up to 1THz (Richard+, 2012) J/A+A/544/A82 : Rotational spectroscopy of diisocyanomethane (Motiyenko+ 2012) J/A+A/548/A71 : Spectroscopy and ISM detection of formamide (Motiyenko+, 2012) J/A+A/549/A96 : mm and sub-mm spectra of 13C-glycolaldehydes (Haykal+, 2013) J/A+A/549/A128 : Singly deuterated isotopologues of formamide (Kutsenko+, 2013) J/A+A/552/A117 : Mono-deuterated dimethyl ether (Richard+, 2013) J/A+A/553/A84 : (Sub)mm spectrum of deuterated methyl cyanides (Nguyen+, 2013) J/A+A/559/A44 : Rotational spectrum of MAAN (CH_2_NCH_2_CN) (Motiyenko+, 2013) J/A+A/563/A137 : THz spectrum of methylamine (Motiyenko+, 2014) J/A+A/568/A58 : HCOO^13^CH_3_ rotational spectrum (Haykal+, 2014) J/A+A/579/A46 : Mono^13^C acetaldehydes mm/submm wave spectra (Margules+ 2015) J/A+A/591/A110 : ^15^NH_2_ amidogen radical rotational spectrum (Margules+, 2016) J/A+A/601/A50 : Sub-millimeter spectra of 2-hydroxyacetonitrile (Margules+, 2017) Byte-by-byte Description of file: s1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 --- J" Upper J quantum number 5- 6 I2 --- Ka" Upper Ka quantum number 7- 9 I3 --- Kc" Upper Kc quantum number 10- 12 I3 --- J' Lower J quantum number 14- 15 I2 --- Ka' Lower Ka quantum number 16- 18 I3 --- Kc' Lower Kc quantum number 39- 50 F12.5 --- Freq Observed transition frequency 56- 63 F8.5 --- O-C Observed - Calculated frequencies 68- 74 F7.5 --- unc Uncertainty of measurements -------------------------------------------------------------------------------- Description of file: File s2.lin (measured transition): ------------------------------------------------------------------------------ Bytes Format Units Label Explanations ------------------------------------------------------------------------------ 1- 3 I2 --- J" Upper J quantum number 5- 6 I2 --- Ka" Upper Ka quantum number 8- 9 I2 --- Kc" Upper Kc quantum number 11- 12 I2 --- J' Lower J quantum number 14- 15 I2 --- Ka' Lower Ka quantum number 17- 18 I2 --- Kc' Lower Kc quantum number 50- 59 F10.3 --- Freq Observed transition frequency 63- 67 F5.3 --- unc Uncertainty of measurements 69- 72 F4.2 --- WT relative weight of line within a blend ------------------------------------------------------------------------------ File s3.par (spectroscopic parameters): First 3 lines for SFIPT use (see https://www.astro.uni-koeln.de/cdms/pickett) For lines 4 to 66: ------------------------------------------------------------------------------ Bytes Format Units Label Explanations ------------------------------------------------------------------------------ 9- 13 I5 --- IDPAR coding of the parameter 16- 37 E22.15 --- PAR parameter value 39- 52 E14.8 --- ERPAR parameter uncertainty 54- 64 A11 --- LABEL parameter label that is delimited by / ------------------------------------------------------------------------------ File s4.cat (spectrum prevision): ------------------------------------------------------------------------------ Bytes Format Units Label Explanations ------------------------------------------------------------------------------ 3- 13 F12.4 MHz FREQ Frequency of the line 16- 21 F8.4 MHz ERR Estimated or experimental error 23- 29 F7.4 --- LGINT Base 10 logarithm of the integrated intensity in units of nm2 MHz 31 I1 --- DR Degrees of freedom in the rotational partition function 33- 41 F9.4 --- ELO Lower state energy in wavenumbers 42- 44 I3 --- GUP Upper state degeneracy 47- 51 I5 --- TAG Species tag or molecular identifier 53- 55 I4 --- QNFMT Identifies the format of the quantum numbers given in the field QN 56- 57 I2 --- J" Upper J quantum number 58- 59 I2 --- Ka" Upper Ka quantum number 60- 61 I2 --- Kc" Upper Kc quantum number 68- 69 I2 --- J' Lower J quantum number 70- 71 I2 --- Ka' Lower Ka quantum number 72- 73 I2 --- Kc' Lower Kc quantum number ------------------------------------------------------------------------------ Acknowledgements: Laurent Margules, Laurent.Margules(at)univ-lille.fr ================================================================================ (End) Laurent Margules [Phlam, France], Patricia Vannier [CDS] 24-Jan-2018