Terahertz and far-infrared synchrotron spectroscopy and global modeling of methyl mercaptan, CH332SH

2012 ◽  
Vol 137 (10) ◽  
pp. 104313 ◽  
Author(s):  
Li-Hong Xu ◽  
R. M. Lees ◽  
G. T. Crabbe ◽  
J. A. Myshrall ◽  
H. S. P. Müller ◽  
...  
Keyword(s):  
Far Infrared ◽  
Methyl Mercaptan ◽  
Global Modeling ◽  
Synchrotron Spectroscopy

Synchrotron spectroscopy of the CSH-bending and CH3-rocking bands of methyl mercaptan

2020 ◽  
Vol 98 (6) ◽  
pp. 519-529
Author(s):  
R.M. Lees ◽  
E.M Reid ◽  
Li-Hong Xu ◽  
B.E. Billinghurst
Keyword(s):  
Ground State ◽  
Vibrational Mode ◽  
Good Representation ◽  
Methyl Mercaptan ◽  
Vibrational Modes ◽  
Oscillatory Structure ◽  
Out Of Plane ◽  
Type Character ◽  
Fourier Transform Spectra ◽  
Synchrotron Spectroscopy

The CSH-bending and CH3-rocking infrared bands of CH3SH have been investigated in Fourier transform spectra recorded at 0.001 cm−1 resolution employing synchrotron radiation at the Canadian Light Source in Saskatoon. The relative band strengths and structures are quite different from those of the CH3OH methanol analogue, with the CSH bend being very weak and both the in-plane and out-of-plane CH3 rocks being strong with intensities greater than the C–S stretch. The CSH bend has parallel a-type character with no detectable b-type component. The out-of-plane CH3 rock is a purely c-type perpendicular band, whereas the in-plane rock is of mixed a/b character. Sub-bands have been assigned for A and E torsional species up to about K = 10 for each vibrational mode, providing upper-state term values from which K-reduced substate origins were determined. For the CSH bend, the origins follow the customary oscillatory torsional pattern as a function of K with a sharply reduced amplitude of 0.362 cm−1 compared to the 0.653 cm−1 for the ground state. The torsional energy curves for the out-of-plane rock are also well-behaved but have inverted ordering of the A–E torsional splitting components and a larger amplitude of 1.33 cm−1. In contrast, the substate origins for the in-plane rock are scattered over a range of about 2 cm−1 without clear oscillatory structure. Several instances of coupling among the lower modes and the ground state via resonances between accidentally near-degenerate levels have been observed and characterized. Ab initio calculations are found to give a good representation of the frequency and relative intensity patterns for the lower vibrational modes.

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.

The far infrared spectrum of methyl mercaptan from 15 cm−1 to 45 cm−1

1967 ◽  
Vol 23 (4) ◽  
pp. 425-438 ◽  
Author(s):  
E.D. Palik ◽  
Donald G. Burkhard ◽  
Robert L. Wallis
Keyword(s):  
Infrared Spectrum ◽  
Far Infrared ◽  
Methyl Mercaptan

FTIR synchrotron spectroscopy of the S–H stretching fundamental of the 12CH332SH species of methyl mercaptan

2018 ◽  
Vol 116 (23-24) ◽  
pp. 3554-3563 ◽  
Author(s):  
R. M. Lees ◽  
Li-Hong Xu ◽  
S. Twagirayezu ◽  
D. S. Perry ◽  
M. B. Dawadi ◽  
...  
Keyword(s):  
Methyl Mercaptan ◽  
Synchrotron Spectroscopy
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