Internal methyl rotation and molecular structure of trifluorotoluenes: microwave rotational spectra of 2,3,4- and 2,4,5-trifluorotoluene

2020 ◽  
Vol 98 (6) ◽  
pp. 543-550 ◽  
Author(s):  
K.P. Rajappan Nair ◽  
Sven Herbers ◽  
Daniel A. Obenchain ◽  
Jens-Uwe Grabow
Keyword(s):  
Internal Rotation ◽  
Rotation Axis ◽  
Molecular Constants ◽  
Methyl Carbon ◽  
Rotational Spectra ◽  
Pulsed Jet ◽  
Principal Axes ◽  
The Moment ◽  
Centrifugal Distortion Constants ◽  
Methyl Rotation

The microwave rotational spectra of 2,3,4- and 2,4,5-trifluorotoluenes, along with all 13C isotopic species in natural abundance, have been recorded in the frequency range 8–27 GHz employing pulsed-jet Fourier transform microwave spectroscopy. The analysis of the spectra in the lowest torsional state has yielded the rotational constants, centrifugal distortion constants, three-fold barrier to methyl rotation, and the direction of the internal rotation axis in the moment of inertia principal axes systems of these trifluorotoluenes. For both molecules, the molecular constants of their eight isotopologues have been used to obtain the substitution rs structures of the ring and the methyl-carbon. The potential barriers hindering the internal rotation of the methyl top in 2,3,4- and 2,4,5-trifluorotluene are 2.5878(80) and 2.2809(23) kJ/mol, respectively.

scholarly journals High Resolution Microwave Spectra of Pyridine-N-oxideanda-Picoline-N-oxide

1989 ◽  
Vol 44 (12) ◽  
pp. 1196-1200 ◽  
Author(s):  
N. Heineking ◽  
H. Dreizler ◽  
K. Endo ◽  
Y. Kamura
Keyword(s):  
High Resolution ◽  
Internal Rotation ◽  
Microwave Spectroscopy ◽  
Coupling Constants ◽  
Centrifugal Distortion ◽  
Rotational Spectra ◽  
Microwave Spectra ◽  
Quadrupole Coupling ◽  
Rotation Motion ◽  
Centrifugal Distortion Constants

Abstract The rotational spectra of pyridine-N-oxide and x-picoline-N-oxide ( = 2-methvlpyridine-N-oxide) have been observed by means of pulsed microwave spectroscopy. For both molecules, the 14N quadrupole coupling constants have been obtained. For α-picoline-N-oxide. in addition the parameters of the internal rotation motion and the centrifugal distortion constants have been determined.

The millimetre-wave spectrum of dimethylsulfide: internal-rotation and centrifugal-distortion analysis

1987 ◽  
Vol 65 (9) ◽  
pp. 1159-1163 ◽  
Author(s):  
J. M. Vacherand ◽  
G. Wlodarczak ◽  
A. Dubrulle ◽  
J. Demaison
Keyword(s):  
Internal Rotation ◽  
Wave Spectrum ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Geometrical Structures ◽  
Millimetre Wave ◽  
Distortion Analysis ◽  
Wave Range ◽  
The Moment ◽  
Centrifugal Distortion Constants

The rotational spectrum of dimethylsulfide has been measured in the millimetre-wave range between 140 and 300 GHz. A new computer program based on the internal-axis method has been used to analyze the rotational spectrum in its torsional ground state. It has allowed us to fit the spectrum satisfactorily and to determine the rotational, internal-rotation, and centrifugal-distortion constants accurately. The influence of the approximations made during the internal-rotation analysis on the moment of inertia (Ia, Ib, Ic, and Iα) is pointed out. It shows the difficulty in determining accurate geometrical structures of two-top molecules from microwave data. For the AA substate, effective rotational parameters are given that allow the calculation of transition frequencies of possible astrophysical interest.

Efficient Treatment of Gyroscopic Bodies in the Recursive Solution of Multibody Dynamics Equations

2008 ◽  
Vol 3 (4) ◽  
Author(s):  
Martin M. Tong
Keyword(s):  
Center Of Mass ◽  
Solution Process ◽  
Body System ◽  
Efficient Treatment ◽  
Composite Body ◽  
Recursive Solution ◽  
System A ◽  
Principal Axes ◽  
Solution Methods ◽  
The Moment

This paper presents an efficient treatment of gyroscopic bodies in the recursive solution of the dynamics of an N-body system. The bodies of interest include the reaction wheels in satellites, wheels on a car, and flywheels in machines. More specifically, these bodies have diagonal inertia tensors. They spin about one of its principal axes, with the moment of inertia along the transverse axes identical. Their center of mass lies on the spin axis. Current recursive solution methods treat these bodies identically as any other body in the system. The proposition here is that a body with gyroscopic children can be collectively treated as a composite body in the recursive solution process. It will be shown that this proposition improves the recursive solution speed to the order(N−m) where m is the number of gyroscopic bodies in the system. A satellite with three reaction wheels is used to illustrate the proposition.

Finding Principal Axes of Complex Plane Rigid Body with Rending-Image of MATLAB

2012 ◽  
Vol 490-495 ◽  
pp. 2156-2159
Author(s):  
Wu Gang Li
Keyword(s):  
Rigid Body ◽  
Complex Plane ◽  
Principal Axis ◽  
Flat Surface ◽  
Moment Of Inertia ◽  
Principal Axes ◽  
The Moment

In order to find the principal axes of inertia and calculate their moment of inertia to any plane homogeneous rigid body for calculating easily the moment of inertia to any axis of this rigid body, the principal axes could be found and their moment of inertia could be calculated automatically by using the reading-image of MATLAB to read the image messages about the flat surface of the rigid body and by the procedures which ware made according to the logic relation about the principal axis and the moment of inertia of the rigid body. Applying this method in a homogeneous cube, a result was acquired, error of which is small compared with the theoretical value. So this method is reliable, convenient and practical

The Rotational Spectrum of Monothioformic Acid. I. cis-and trans-HC(:O)SH1,2

1976 ◽  
Vol 31 (5) ◽  
pp. 422-437
Author(s):  
William H. Hocking ◽  
Gisbert Winnewisser
Keyword(s):  
Frequency Region ◽  
Absorption Lines ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Astrophysical Interest ◽  
Rotational Spectra ◽  
Measured Line ◽  
Centrifugal Distortion Constants ◽  
Cis And Trans ◽  
Line Positions

Abstract The rotational spectra of the two abundant isomers of monothioformic acid, cis- and trans- HC(:O)SH, have been assigned in the frequency region 8 -250 GHz. Over 90 a-type transitions and over 60 b-type transitions have been measured for each rotamer. The a-type transitions belong to the qRK , qQ1, qQ2, qQ3 and qQ4 branches and the b-type absorption lines encompass the Ka = 1 - 0, 2 - 1, 3 - 2, 4 - 3 and 5 - 4 rotational sub-bands. The rotational constants and all quartic and sextic centrifugal distortion constants have been determined for each rotamer using Watson's reduced Hamiltonian. In addition to the measured line positions the frequencies of some selected low-J transitions, not observed in this work but of potential astrophysical interest, have been listed as an aid in the interstellar search for monothioformic acid.

High Resolution Microwave Spectroscopy of Ethyl Vinyl Ether: Accurate Determination of the Methyl Top Internal Rotation Barrier

2000 ◽  
Vol 55 (5) ◽  
pp. 481-485 ◽  
Author(s):  
H. Dreizler ◽  
N. Hansen
Keyword(s):  
Internal Rotation ◽  
Vinyl Ether ◽  
Accurate Determination ◽  
Ethyl Vinyl Ether ◽  
Ethyl Vinyl ◽  
Methyl Group ◽  
Rotational Spectra ◽  
Internal Rotation Barrier ◽  
In Trans

Abstract We have performed an investigation of the internal rotation of the methyl group in trans-cis ethyl vinyl ether by using molecular beam-Fourier transform Microwave (MB-FTMW) spectroscopy. Rotational spectra (up to J = 20) were recorded in the frequency region 4-19 GHz. Due to the internal rotation of the methyl group, some rotational transitions were split and the torsional barrier could be determined to V3 (CH3) = 1074.4(4) cm-1 .

scholarly journals Microwave Spectrum and Nuclear Quadrupole Interaction of 3-Bromothiophene in Excited Vibrational States

1983 ◽  
Vol 38 (12) ◽  
pp. 1309-1319 ◽  
Author(s):  
Yoshiaki Sasada
Keyword(s):  
Excited States ◽  
Nuclear Quadrupole Interaction ◽  
Coupling Constants ◽  
Vibrational Modes ◽  
Centrifugal Distortion ◽  
Vibrational States ◽  
Rotational Spectra ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Centrifugal Distortion Constants

Abstract The rotational spectra of 3-bromothiophene in the excited states of two vibrational modes were observed and the rotational constants, the centrifugal distortion constants, and the nuclear quadrupole coupling constants were determined. The wave numbers of the two vibrational modes were evaluated to be 210 cm-1 and 320 cm-1 by measuring relative intensities of the ground and excited vibrational transitions. Variations in the inertia defect for each of the vibrational modes are compared with the results of the approximate calculation.

Rotational Spectrum of Aminoborane: Centrifugal Distortion Constants and Boron and Nitrogen Hyperfine Structure

1991 ◽  
Vol 46 (9) ◽  
pp. 770-776 ◽  
Author(s):  
Kirsten Vormann ◽  
Helmut Dreizler ◽  
Jens Doose ◽  
Antonio Guarnieri
Keyword(s):  
Hyperfine Structure ◽  
Spin Rotation ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Rotational Spectra ◽  
Quadrupole Coupling ◽  
Wave Region ◽  
Nuclear Quadrupole ◽  
Centrifugal Distortion Constants

AbstractThe boron and nitrogen hyperfine structure in the rotational spectra of two aminoborane isotopomers, 11 BH2NH2 and 10BH2NH2, has been investigated and the quadrupole coupling constants of boron 10B, 11B and nitrogen 14N have been determined. We get the following results for the nuclear quadrupole coupling constants: χaa(11B) = -1.684 (14) MHz, χbb(11B) = -2.212 (11) MHz, χcc(11B) = 3.896(11) MHz, χaa(10B) = -3.481 (11) MHz, χbb(10B) = -4.623 (14) MHz, χCC(10B) = 8.104 (14) MHz and xaa(14N) = 0.095 (9) MHz, χbb(14N) = 2.091 (8) MHz, χcf4 (14N)=-2.186 (8) MHz. These nitrogen quadrupole coupling constants are those of the 11BH2 NH2 isotopomer. Additionally we were able to determine two out of the three spin rotation coupling constants caa, cbb, and ccc of boron, caa(11 B = 55.2 (26) kHz, cbb(11B) = 6.62 (36) kHz, caa (10B) = 15.26 (69) kHz and cbb(10B) = 4.94 (70) kHz. The spin rotation coupling constants ccc had to be fixed to zero in both cases. Furthermore we measured the rotational spectra in the mm-wave region to determine all quartic and several sextic centrifugal distortion constants according to Watson's A and S reduction

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