scholarly journals Rotational spectroscopy of isotopic species of methyl mercaptan at millimeter and submillimeter wavelengths: CH334SH

2019 ◽  
Vol 627 ◽  
pp. A41 ◽  
Author(s):  
Olena Zakharenko ◽  
Frank Lewen ◽  
Vadim V. Ilyushin ◽  
Holger S. P. Müller ◽  
Stephan Schlemmer ◽  
...  
Keyword(s):  
Group Versus ◽  
Rotational Spectroscopy ◽  
Methyl Mercaptan ◽  
Rotational Spectrum ◽  
Experimental Accuracy ◽  
Terrestrial Environment ◽  
Natural Isotopic Abundance ◽  
Molecular Core ◽  
Submillimeter Wavelengths ◽  
Millimeter And Submillimeter Wavelengths

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 CH334SH, which is complicated by the large-amplitude internal rotation of the CH3 group versus the 34SH frame, was investigated in the 49−510 GHz and 1.1−1.5 THz 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.

scholarly journals Rotational spectroscopy of methyl mercaptan CH332SH at millimeter and submillimeter wavelengths

2019 ◽  
Vol 629 ◽  
pp. A73 ◽  
Author(s):  
Olena Zakharenko ◽  
Vadim V. Ilyushin ◽  
Frank Lewen ◽  
Holger S. P. Müller ◽  
Stephan Schlemmer ◽  
...  
Keyword(s):  
Far Infrared ◽  
Rotational Spectroscopy ◽  
Methyl Mercaptan ◽  
Mean Square ◽  
Mean Square Deviation ◽  
Astronomical Observations ◽  
Quantum Numbers ◽  
Submillimeter Wavelengths ◽  
Global Study ◽  
Millimeter And Submillimeter Wavelengths

We present a new global study of the millimeter (mm) wave, submillimeter (sub-mm) wave, and terahertz (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 sub-mm 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 fit 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 (MW) and 16 345 far-infrared line frequencies sampling transitions within and between the ground, first, and second excited torsional states. This investigation presents a two-fold expansion in the J quantum numbers and a significant improvement in the fit quality, especially for the MW part of the data, thus allowing us to provide more reliable predictions to support astronomical observations.

scholarly journals Deuterated methyl mercaptan (CH3SD): Laboratory rotational spectroscopy and search toward IRAS 16293–2422 B

2019 ◽  
Vol 621 ◽  
pp. A114 ◽  
Author(s):  
Olena Zakharenko ◽  
Frank Lewen ◽  
Vadim V. Ilyushin ◽  
Maria N. Drozdovskaya ◽  
Jes K. Jørgensen ◽  
...  
Keyword(s):  
Rotational Spectroscopy ◽  
Mass Star ◽  
Methyl Mercaptan ◽  
Rotational Spectrum ◽  
Star Forming ◽  
Star Forming Regions ◽  
Millimeter Wavelengths ◽  
Low Mass ◽  
Line Survey ◽  
Telescope Arrays

Methyl mercaptan (also known as methanethiol), CH3SH, 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 CH3SD to facilitate astronomical observations by radio telescope arrays at (sub)millimeter wavelengths. We have measured the rotational spectrum associated with the large-amplitude internal rotation of the methyl group of methyl mercaptan using an isotopically enriched sample in the 150−510 GHz frequency range using the Köln millimeter wave spectrometer. The analysis of the spectra has been performed up to the second excited torsional state. We present modeling results of these data with the RAM36 program. CH3SD 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%.

Barrier to internal rotation, symmetry and carbonyl reactivity in methyl 3,3,3-trifluoropyruvate

2020 ◽  
Vol 234 (7-9) ◽  
pp. 1383-1393 ◽  
Author(s):  
Kevin Gregor Lengsfeld ◽  
Philipp Buschmann ◽  
Pavel Kats ◽  
Dirk Siekmann ◽  
Sven Herbers ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Chemical Properties ◽  
Rotational Spectroscopy ◽  
Rotational Spectrum ◽  
Experimental Accuracy ◽  
Rotation Symmetry ◽  
Barrier Heights ◽  
Large Amplitude Motions ◽  
Conformational Landscape

AbstractHigh-resolution rotational spectroscopy was used to investigate the conformational landscape of methyl-3,3,3-trifluoropyruvate, a small, partially-fluorinated molecule, which is of interest because of its chemical properties and reactivity in contrast to the unfluorinated species. Methyl 3,3,3-trifluoropyruvate is also subject to two possible large amplitude motions of the methyl and trifluoromethyl group. However, only the methyl rotor gives rise to the tunneling splitting specific to individual conformers. In the rotational spectrum measured in the frequency region from 6 to 27 GHz, the identified conformers, s-cis and s-trans, were fitted to experimental accuracy, resulting in the accurate determination of the vibrational ground state rotational constants ${A}_{0}=2185.05827\left(36\right)\text{\hspace{0.17em}MHz}$, ${B}_{0}=1023.30031\left(17\right)\text{\hspace{0.17em}MHz}$, and ${C}_{0}=803.520287\left(95\right)\text{\hspace{0.17em}MHz}$ for the s-cis conformer, and ${A}_{0}=2706.9024\left(49\right)\text{\hspace{0.17em}MHz}$, ${B}_{0}=864.889539\left(81\right)\text{\hspace{0.17em}MHz}$, and ${C}_{0}=746.532896\left(71\right)\text{\hspace{0.17em}MHz}$ for the s-trans conformer. Additionally the barrier heights of the methyl rotor ${V}_{3}\left({\text{CH}}_{3}\right)=363.116\left(94\right){\text{\hspace{0.17em}cm}}^{-1}$ and ${V}_{3}\left({\text{CH}}_{3}\right)=389.290\left(80\right){\text{\hspace{0.17em}cm}}^{-1}$ were obtained for the s-cis and s-trans conformer, respectively.

THE PURE ROTATIONAL SPECTRUM OF PbI FROM BROADBAND ROTATIONAL SPECTROSCOPY

2014 ◽  
Author(s):  
Daniel Zaleski ◽  
Corey Evans ◽  
Lisa-Maria Dickens ◽  
Nick Walker ◽  
Susanna Stephens ◽  
...  
Keyword(s):  
Rotational Spectroscopy ◽  
Rotational Spectrum

scholarly journals Profiled Horn Antenna with Wideband Capability Targeting Sub-THz Applications

Electronics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 412
Author(s):  
Jay Gupta ◽  
Dhaval Pujara ◽  
Jorge Teniente
Keyword(s):  
Hermite Polynomial ◽  
Polynomial Interpolation ◽  
Horn Antenna ◽  
Submillimeter Wavelengths ◽  
Thz Applications ◽  
Millimeter And Submillimeter Wavelengths ◽  
Better Than

This paper proposes a wideband profiled horn antenna designed using the piecewise biarc Hermite polynomial interpolation and validated experimentally at 55 GHz. The proposed design proves S11 and directivity better than −22 dB and 25.5 dB across the entire band and only needs 3 node points if compared with the well-known spline profiled horn antenna. Our design makes use of an increasing radius and hence does not present non-accessible regions from the aperture, allowing its fabrication with electro erosion techniques especially suitable for millimeter and submillimeter wavelengths.

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