Laboratory microwave spectrum of C-13H(3)OH

Kuriyama, H.; Takagi, Kojiro; Takeo, Harutoshi; Matsumura, Chi

doi:10.1086/164843

Cited by 14 publications

(12 citation statements)

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“…The spectroscopic line data were taken from the CDMS catalog 1 (Müller et al 2001(Müller et al , 2005. The first version is based on Xu et al (1996) and Xu & Lovas (1997) with experimental transition frequencies in the range of our ALMA data from Kuriyama et al (1986) and from the privately communicated methanol atlas of the Toyama University (Tsunekawa et al 1995). An update of the CDMS entry is in preparation.…”

Section: Methanol Ch 3 Ohmentioning

confidence: 99%

Exploring molecular complexity with ALMA (EMoCA): Alkanethiols and alkanols in Sagittarius B2(N2)

Müller

Беллоче

et al. 2016

A&A

139

157

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Context. Over the past five decades, radio astronomy has shown that molecular complexity is a natural outcome of interstellar chemistry, in particular in star forming regions. However, the pathways that lead to the formation of complex molecules are not completely understood and the depth of chemical complexity has not been entirely revealed. In addition, the sulfur chemistry in the dense interstellar medium is not well understood. Aims. We want to know the relative abundances of alkanethiols and alkanols in the Galactic center source Sagittarius B2(N2), the northern hot molecular core in Sgr B2(N), whose relatively small line widths are favorable for studying the molecular complexity in space. Methods. We investigated spectroscopic parameter sets that were able to reproduce published laboratory rotational spectra of ethanethiol and studied effects that modify intensities in the predicted rotational spectrum of ethanol. We used the Atacama Large Millimeter Array (ALMA) in its Cycles 0 and 1 for a spectral line survey of Sagittarius B2(N) between 84 and 114.4 GHz. These data were analyzed by assuming local thermodynamic equilibrium (LTE) for each molecule. Our observations are supplemented by astrochemical modeling; a new network is used that includes reaction pathways for alkanethiols for the first time. Results. We detected methanol and ethanol in their parent 12 C species and their isotopologs with one 12 C atom substituted by 13 C; the latter were detected for the first time unambiguously in the case of ethanol. The 12 C/ 13 C ratio is ∼25 for both molecules. In addition, we identified CH OH ratio of ∼7.3. Upper limits were derived for the next larger alkanols normal-and iso-propanol. We observed methanethiol, CH 3 SH, also known as methyl mercaptan, including torsionally excited transitions for the first time. We also identified transitions of ethanethiol (or ethyl mercaptan), though not enough to claim a secure detection in this source. The ratios CH 3 SH to C 2 H 5 SH and C 2 H 5 OH to C 2 H 5 SH are 21 and 125, respectively. In the process of our study, we noted severe discrepancies in the intensities of observed and predicted ethanol transitions and propose a change in the relative signs of the dipole moment components. In addition, we determined alternative sets of spectroscopic parameters for ethanethiol. The astrochemical models indicate that substantial quantities of both CH 3 SH and C 2 H 5 SH may be produced on the surfaces of dust grains, to be later released into the gas phase. The modeled ratio CH 3 SH/C 2 H 5 SH = 3.1 is lower than the observed value of 21; the model value appears to be affected most by the underprediction of CH 3 SH relative to CH 3 OH and C 2 H 5 OH, as judged by a very high CH 3 OH/CH 3 SH ratio. Conclusions. The column density ratios involving methanol, ethanol, and methanethiol in Sgr B2(N2) are similar to values reported for Orion KL, but those involving ethanethiol are significantly different and suggest that the detection of ethanethiol reported toward Orion KL ...

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Section: Methanol Ch 3 Ohmentioning

confidence: 99%

Exploring molecular complexity with ALMA (EMoCA): Alkanethiols and alkanols in Sagittarius B2(N2)

Müller

Беллоче

et al. 2016

A&A

139

157

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“…(2); Unc Å measurement uncertainty, assigned here for weighting purposes in the global fit; * in the Unc column indicates transitions not included in the fit; O-C Å observed minus calculated residual from the global fit. References: A, (11); B, (12); C, (13); D, (14); E, (15); F, (16); G, (17). perturbations induced by this Dn t Å 1, DK Å 4 resonance squares residuals for subbands connected with these states appear anomalous; hence all of the perturbations are properly are accurately reproduced by the global fit.…”

Section: And Perturbationsmentioning

confidence: 99%

Global Fit of Torsion–Rotation Transitions in the Ground and First Excited Torsional States of13C-Methanol

Walsh

Lees

1996

Journal of Molecular Spectroscopy

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A global treatment of reported microwave, millimeter-wave, and Fourier-transform far-infrared (FIR) spectra of the C-13 isotopic species of methanol has been carried out for the first two torsional states ( n t Å 0 below the barrier and n t Å 1 straddling the barrier) of the ground vibrational state. 42-57 (1984)). A convergent global fit was achieved using 55 adjustable and 2 fixed parameters to reach an overall weighted standard deviation of 0.962, giving further confirmation that a traditional onedimensional internal rotation model can accurately describe methanol energy levels up through the first excited torsional state. Our new parameters for C-13 methanol are compared to previous global fitting results for the normal 12 CH 3 OH isotopomer. Calculations employing these parameters reveal possible C-13 assignments for 28 lines appearing in natural abundance in a newly measured methanol microwave atlas from 7 to 200 GHz compiled by the group at Toyama University in Japan.

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“…Most of the transitions assigned in [1] had Dn = 0 or 1, only a few of them had Dn = 2, n being the torsional quantum number. In the same work, we also observed mixings within three pairs of level sequences of A-symmetry, labeled by the (n, K) quantum numbers: (0, 9)/ (1,5), (1,4)/ (1,6), and (1,8)/ (1,9). These mixings lead to the presence of ''forbidden'' transitions connecting levels with Dn = 1, DK = 0, 2, 3, and Dn = 0, DK = 2.…”

Section: Introductionmentioning

confidence: 53%

“…Altogether, our data files for the torsional transitions of 13 CH 3 OH, available as supplementary data to the present work, now comprise almost 25 550 absorption lines. Of course, our database includes also the older assignments performed by other researchers in the MW and MMW regions [9,10]. Interested spectroscopists can also request our lists by electronic mail (giovanni.moruzzi@df.unipi.it or joca@fqm.feis.unesp.br).…”

Section: Fir Assignments and Discussionmentioning

confidence: 99%

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Systematic analysis of the Fourier transform spectrum of 13CH3OH between 400 and 950cm−1

Moraes¹,

Moruzzi²,

Strumia³

et al. 2005

Journal of Molecular Spectroscopy

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Laboratory microwave spectrum of C-13H(3)OH

Cited by 14 publications

References 0 publications

Exploring molecular complexity with ALMA (EMoCA): Alkanethiols and alkanols in Sagittarius B2(N2)

Exploring molecular complexity with ALMA (EMoCA): Alkanethiols and alkanols in Sagittarius B2(N2)

Global Fit of Torsion–Rotation Transitions in the Ground and First Excited Torsional States of13C-Methanol

Systematic analysis of the Fourier transform spectrum of 13CH3OH between 400 and 950cm−1

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