NORMAL MODES, CORIOLIS COUPLING, AND CENTRIFUGAL DISTORTION IN MOLECULES WITH NEARLY FREE INTERNAL ROTATION: CH3—C≡C—CH3 AND CH3—C≡C—SiH3

1967 ◽  
Vol 45 (12) ◽  
pp. 3867-3893 ◽  
Author(s):  
P. R. Bunker ◽  
J. T. Hougen
Keyword(s):  
Force Field ◽  
Internal Rotation ◽  
Energy Levels ◽  
Normal Modes ◽  
Force Constants ◽  
Coupling Constants ◽  
Torsional Angle ◽  
Coriolis Coupling ◽  
Centrifugal Distortion ◽  
Centrifugal Distortion Constants

In 1964 Duncan determined force fields for the molecules CH3—C≡C—CH3 and CH3—C≡C—SiH3 under the assumption that the force constants were not dependent on the torsional angle γ. In the first half of this paper we determine the quantitative effect of adding various γ-dependent force constants to Duncan's force field for CH3—C≡C—CH3. The results lead to complications concerning the symmetry species of the normal coordinates, the magnitude of the Coriolis coupling constants, and the calculation of the energy levels. The possible avoidance of these complications is discussed.In the second half of the paper a formalism is set up relating the rotational and torsional centrifugal distortion constants to the vibrational force field for certain molecules with nearly free internal rotation. Duncan's force field for CH3—C≡C—SiH3 is used to calculate some centrifugal distortion constants for that molecule and for CH3—C≡C—SiD3 on the assumption of completely free internal rotation. Good agreement is obtained between the quantities calculated here and the observed quantities determined by Kirchhoff and Lide.

Vibrational Analysis of SnCl4N and SnBr4N

1981 ◽  
Vol 36 (6) ◽  
pp. 630-633
Author(s):  
V. Sengodan ◽  
K. G. Srinivasacharya
Keyword(s):  
Secular Equation ◽  
Vibrational Analysis ◽  
Force Constants ◽  
Coupling Constants ◽  
Coriolis Coupling ◽  
Centrifugal Distortion ◽  
Molecular Constants ◽  
Mean Amplitudes Of Vibration ◽  
Experimental Values ◽  
Centrifugal Distortion Constants

Abstract The kinetic constants method is applied to evaluate a fresh set of force constants in case of SnCl4N and SnBr4N, using recent vibrational frequencies. Certain simplifying considerations involving molecular dynamics are made use of in solving the secular equation. The calculated kinetic and force constants are utilised to evaluate other molecular constants, namely mean amplitudes of vibration, Coriolis coupling constants and centrifugal distortion constants. The calculated mean amplitudes of vibration of the Sn-Br bond (SnBr4N) are within the range of the available experimental values (SnBr4)

On the Applicability of Redington's Method of Determination of Force Field to Bent XYZ Type Systems

1979 ◽  
Vol 34 (6) ◽  
pp. 716-720 ◽  
Author(s):  
R. Namasivayam ◽  
S. Mayilavelan
Keyword(s):  
Type Systems ◽  
Coupling Constants ◽  
Coriolis Coupling ◽  
Centrifugal Distortion ◽  
Molecular Constants ◽  
Mean Amplitudes Of Vibration ◽  
Method Of Determination ◽  
Point Solution ◽  
Centrifugal Distortion Constants

Abstract Force fields of NSF, NSCl, NSBr, SSO, HCO, HOF, HOCl, HOBr and HOI have been computed using Redington’s method. The angle parameters φ12, φ13 and φ23 are fixed through Fsteep critical point solution. The parametrised eigenvector matrices obtained are found to possess the properties predicted by Peacock et al. Mean amplitudes of vibration, Coriolis coupling constants, inertia defects and centrifugal distortion constants have also been calculated and compared with literature values. Redington’s approach is found to reproduce all the molecular constants with accuracies comparable with conventional methods.

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 microwave spectrum, harmonic force field, structure, and dipole moment of propiolyl chloride

1982 ◽  
Vol 60 (6) ◽  
pp. 679-689 ◽  
Author(s):  
R. Wellington Davis ◽  
M. C. L. Gerry
Keyword(s):  
Dipole Moment ◽  
Force Field ◽  
Coupling Constants ◽  
Centrifugal Distortion ◽  
Vibrational States ◽  
Harmonic Force ◽  
Isotopic Species ◽  
Quadrupole Coupling ◽  
Centrifugal Distortion Constants ◽  
Vibrational Wavenumbers

The microwave spectra of four isotopic species of propiolyl chloride, HCCCOCl, have been measured for their ground and υ9 = 1 excited vibrational states. Values for the rotational constants, quartic centrifugal distortion constants, chlorine nuclear quadrupole coupling constants, and the molecular dipole moment have been obtained. The centrifugal distortion constants have been combined with vibrational wavenumbers from the literature to calculate an approximate harmonic force field. Effective and ground state average structures of the most abundant isotopic species, H12C12C12C16O35Cl, are presented.

On Centrifugal Distortion and Urey-Bradley Force Field of Chlorofluoromethane

1979 ◽  
Vol 34 (8) ◽  
pp. 954-956 ◽  
Author(s):  
A. I. Jaman ◽  
R. N. Nandi
Keyword(s):  
Force Field ◽  
Field Model ◽  
Vibrational Frequencies ◽  
Force Constants ◽  
Centrifugal Distortion ◽  
Normal Coordinate ◽  
Internal Coordinates ◽  
Centrifugal Distortion Constants ◽  
Coordinate Treatment ◽  
Good Agreement

Abstract A normal coordinate treatment of chlorofluoromethane has been performed in the Urey-Bradley force field model using the centrifugal distortion constants and the vibrational frequencies. Since the molecule has only one plane of symmetry (Cs), the symmetrized internal coordinates have not been used in the calculation. The effect of the angular redundancy has been rigorously treated and the derived force constants are in good agreement with those of other halogenated methane.

33S Nuclear Hyperfine Structure in the Rotational Spectrum of Thiazole

1993 ◽  
Vol 48 (12) ◽  
pp. 1219-1222 ◽  
Author(s):  
U. Kretschmer ◽  
H. Dreizler
Keyword(s):  
Fourier Transform ◽  
Hyperfine Structure ◽  
Molecular Beam ◽  
Microwave Spectroscopy ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Centrifugal Distortion Constants

Abstract We investigated the 33S nuclear quadrupole coupling of thiazole- 33S in natural abundance by molecular beam Fourier transform microwave spectroscopy. In addition the 14N nuclear quadrupole coupling could be analyzed with high precision. We derived the rotational constants A = 8529.29268 (70) MHz, B = 5427.47098 MHz, and C = 3315.21676 (26) MHz, quartic centrifugal distortion constants and the quadrupole coupling constants of 33S χaa = 7.1708 (61) MHz and χbb= -26.1749 (69) MHz and of 14N χ aa = -2.7411 (61) MHz and χbb = 0.0767 (69) MHz.

The microwave spectrum of the ClS2 free radical

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1043-1050 ◽  
Author(s):  
Masaharu Fujitake ◽  
Eizi Hirota
Keyword(s):  
Free Radical ◽  
Force Field ◽  
Electronic Spectroscopy ◽  
Spin Rotation ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Harmonic Force ◽  
Isotopic Species ◽  
Spin Resonance ◽  
Centrifugal Distortion Constants

The rotational spectrum of the ClS2 free radical in the gaseous phase has been observed in the millimetre- and submillimetre-wave regions. The ClS2 radical was generated by a dc glow discharge in either S2Cl2 or SCl2. Both a- and b-type R-branch transitions, most of which were split into two fine structure components, were detected for both of the 35Cl and 37Cl isotopic species in the ground vibronic state. As expected from the small hyperfine interaction constants reported by an electron spin resonance (ESR) study, the hyperfine structure was resolved for none of the transitions observed in the present study. Analysis of the observed transition frequencies yielded rotational and centrifugal distortion constants and also spin–rotation interaction constants with their centrifugal corrections. The spin–rotation interaction constants obtained in the present study were consistent with g values of the ESR study. The rotational constants of the two isotopic species led to the structure parameters r(S—S) = 1.906 (7) Å, r(S—Cl) = 2.071 (5) Å, and θ(SSCl) = 110.3 (4)°. A harmonic force field was derived from the observed centrifugal distortion constants and inertial defects combined with the ν1 frequency reported in literature on electronic spectroscopy. This harmonic force field yielded the ν2 and ν3 frequencies (445 (21) and 213.0 (2) cm−1, respectively, for 35ClS2), which differed considerably from the values reported previously.

The Vibrational Spectrum and Urey-Bradley Force Constants of the Trifluoromethyltrifluoroborate(1-) Anion

1973 ◽  
Vol 27 (3) ◽  
pp. 209-213 ◽  
Author(s):  
John F. Jackovitz ◽  
Charles E. Falletta ◽  
James C. Carter
Keyword(s):  
Potential Energy ◽  
Vibrational Spectrum ◽  
Energy Distribution ◽  
Force Field ◽  
Raman Spectra ◽  
Normal Modes ◽  
Force Constants ◽  
Potential Energy Distribution ◽  
Infrared And Raman Spectra ◽  
Normal Coordinate

Infrared and Raman spectra for (K+) (CF3BF3−) have been obtained from 4000 to 50 cm−1. Spectral assignments were made on the basis of C3v symmetry using both 10B and 11B compounds. In addition, a normal coordinate analysis was performed to obtain the potential energy distribution of the normal modes. A Urey-Bradley type force field was used, and force constants obtained for the CF3 and BF3 groupings were compared to those in C2F6 and BF4−.

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