Millimeter-Wave Spectrum of Ethyl Acetylene Centrifugal Distortion, Coriolis Interaction and Internal Rotation

1983 ◽  
Vol 38 (4) ◽  
pp. 447-451 ◽  
Author(s):  
J. Demaison ◽  
D. Boucher ◽  
J. Burie ◽  
A. Dubrulle
Keyword(s):  
Excited State ◽  
Internal Rotation ◽  
Plane Deformation ◽  
Wave Spectrum ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Coriolis Interaction ◽  
Methyl Group ◽  
First Excited State ◽  
Methyl Torsion

The rotational spectrum of ethyl acetylene has been investigated between 70 and 320 GHz. A Coriolis interaction has been found between the first excited state of the methyl torsion and the C - C = C in plane deformation. Splittings of transitions in the first excited torsional state show that the barrier hindering internal rotation of the methyl group amounts to 3271 cal/mole.

scholarly journals Microwave Spectrum of Ethyl Iodid: Internal Rotation Analysis

1980 ◽  
Vol 35 (4) ◽  
pp. 442-446 ◽  
Author(s):  
D. Boucher ◽  
A. Dubrulle ◽  
J. Demaison
Keyword(s):  
Internal Rotation ◽  
Plane Deformation ◽  
Microwave Spectrum ◽  
The Other ◽  
Kcal Mole ◽  
Coriolis Interaction ◽  
Methyl Group ◽  
Rotational Spectra ◽  
First Excited State ◽  
Methyl Torsion

Abstract The rotational spectra of the first excited state of the methyl torsion and the CCI-in plane deformation of CH3CH2I have been studied. A Coriolis interaction between these two modes has been found. Splittings of transitions in the first excited torsional state show that the barrier hindering internal rotation of the methyl group is 3.62 kcal/mole. This value agrees quite well with the value previously reported from Raman studies. It is internally consistent and similar to the other ethyl halides.

Millimeter-Wave Spectrum of Ethyl Formate

1984 ◽  
Vol 39 (6) ◽  
pp. 560-564 ◽  
Author(s):  
J. Demaison ◽  
D. Boucher ◽  
J. Burie ◽  
A. Dubrulle
Keyword(s):  
Internal Rotation ◽  
Millimeter Wave ◽  
Wave Spectrum ◽  
Ethyl Formate ◽  
Rotational Spectrum ◽  
Kcal Mole ◽  
Methyl Group

The rotational spectrum of ethyl formate has been investigated up to 240 GHz. High J transitions of both a-type and b-type have been measured for the two isomers and fitted to a centrifugally distorted Hamiltonian including some sextic coefficients. The results of the analysis are sufficiently accurate for the prediction of all strong transitions throughout the millimeterwave range. No splitting due to the internal rotation of the methyl group was observed, which indicates that the barrier to internal rotation is of the order of 3 kcal/mole or greater.

Rotation-Torsion-Vibration Interaction in Acetyl Cyanide: Normal and 15N Isotopic Species

1978 ◽  
Vol 33 (2) ◽  
pp. 204-213 ◽  
Author(s):  
G. K. Pandey ◽  
H. Dreizler
Keyword(s):  
Excited State ◽  
Degrees Of Freedom ◽  
Rotational Spectrum ◽  
Vibrational States ◽  
Bending Vibration ◽  
Isotopic Species ◽  
Torsion Vibration ◽  
First Excited State ◽  
Rotational Transitions ◽  
Methyl Torsion

The rotation - torsion - vibration interaction in the normal and 15N isotopic species of Acetyl Cyanide is studied in the rotational spectrum of ground, first excited state of methyl torsion and first excited state of CCN in plane bending vibration. With respect to a previous -work [1] a more detailed check of a model with five degrees of freedom, comprising three for the overall rotation and two for the two lowest vibrations was possible. Potential parameters were fitted simultaneously to the splittings of the rotational transitions in the ground, excited torsional and excited vibrational states for the normal and 15N isotopic species of the molecule. The coefficients V3 and V6 of the Fourier expansion of the hindering potential for the torsion and two interaction constants V3c′ and F3c″ for the torsion and in plane CCN bending vibration were determined, apart from the harmonic force constant k2q for the vibration, which is obtained from the measured infrared data of the normal species. Using these results, the (E-A) splittings of the rotational transitions could be nicely reproduced but not the absolute frequencies of the rotational transitions.

The Millimeter and Submillimeter-Wave Spectrum of Dimethylether

1990 ◽  
Vol 45 (5) ◽  
pp. 702-706 ◽  
Author(s):  
W. Neustock ◽  
A. Guarnieri ◽  
J. Demaison ◽  
G. Wlodarczak
Keyword(s):  
Internal Rotation ◽  
Wave Spectrum ◽  
Submillimeter Wave ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Centrifugal Distortion Constants

Abstract We report the analysis of the rotational spectrum of dimethylether measured between 60 and 400 GHz. Rotational and quartic centrifugal distortion constants are given. Internal rotation splittings are analysed with the I AM method. The value of is compared to the values obtained for similar molecules

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.

Millimetre wave spectrum of methyl mercaptan

1980 ◽  
Vol 58 (11) ◽  
pp. 1640-1648 ◽  
Author(s):  
R. M. Lees ◽  
M. Ali Mohammadi
Keyword(s):  
Interstellar Medium ◽  
Least Squares ◽  
Wave Spectrum ◽  
Methyl Mercaptan ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Millimetre Wave ◽  
Torsion Vibration ◽  
Vibration Rotation ◽  
Centrifugal Distortion Constants

An investigation of the rotational spectrum of CH332SH, one of the most recent molecules to be detected in the interstellar medium, has been carried out over the 25–107 GHz region. The frequencies of a-type Δk = 0 R-branch transitions have been measured for the J = 1 ← 0 up to J = 4 ← 3 multiplets for torsional states νt = 0–3. In addition, many P-, Q-, and R-branch transitions with Δk ≠ 0 have been identified in order to provide a catalogue of lines for potential radio astronomical applications. Improved values of rotational and centrifugal distortion constants, a-type torsion–vibration–rotation interaction constants, and torsional barrier parameters (V3 = 444.76 cm−1; effective V6 = −2.07 cm−1) have been determined from least-squares analyses of the spectra.

Determination of a High Potential Barrier Hindering Internal Rotation from the Ground State Spectrum. The Methylbarrier of Ethylbromide

1985 ◽  
Vol 40 (6) ◽  
pp. 575-587 ◽  
Author(s):  
J. Gripp ◽  
H. Dreizler ◽  
R. Schwarz
Keyword(s):  
Hyperfine Structure ◽  
Internal Rotation ◽  
Potential Barrier ◽  
Ground State ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Vibrational Ground State ◽  
Distortion Analysis ◽  
High Potential Barrier

For ethylbromide a determination of the parameters of internal rotation is given derived from the rotational spectrum of the torsional and vibrational ground state. The Br-hyperfine structure is reanalysed with higher precision. As high J transitions were measured a centrifugal distortion analysis was necessary.

Mikrowellenspektrum, Hinderungspotential der internen Rotation und Dipolmoment des para-Fluortoluols

1965 ◽  
Vol 20 (12) ◽  
pp. 1682-1686 ◽  
Author(s):  
Heinz Dieter Rudolph ◽  
Helmut Seiler
Keyword(s):  
Dipole Moment ◽  
Internal Rotation ◽  
Absorption Lines ◽  
Type I ◽  
Rotational Spectrum ◽  
Rotation Barrier ◽  
Rotational Constants ◽  
Methyl Group ◽  
Microwave Rotational Spectrum ◽  
Internal Rotation Barrier

The microwave rotational spectrum of para-fluoro-toluene has been investigated in the region from 7 to 31 kmc/s. The three types of absorption lines to be expected in the case of a molecule of this type, i. e. with a very low sixfold barrier hindering the internal rotation of the methyl group, have been found: m=0, | m | ≠ 0, 3 n, | m | = 3 n. From the lines m=0 the rotational constants and the dipole moment, (1.96 ± 0.02) D, have been deduced; from the lines |m|=3 the internal rotation barrier could be calculated as V6=13.82 cal/mole. This V6 is compared with the values found for similar molecules.

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