Journal ArticleDOI
Torsion–Vibration–Rotation Interactions in Methanol. I. Millimeter Wave Spectrum
R. M. Lees,J. G. Baker +1 more
TLDR
In this article, Kivelson's formula for a −1 transition was tested over a wide range of quantum numbers, and convergence difficulties in the least square fit of Kirtman's formula were revealed.Abstract:
In a study of internal rotation in methanol, the millimeter wave spectra of CH3OH, CD3OH, and CH3OD have been investigated between 90 and 200 Gc/sec. In the analysis of the spectra, torsion–vibration–rotation interactions were treated as adjustable parameters in semiempirical formulas. Kivelson's formula for a‐type ΔK = 0 transitions was tested over a wide range of quantum numbers. It reproduced the CH3OH and CD3OH spectra quite well, but the approximations used in the calculations appear to start breaking down for the larger asymmetry of CH3OD. For assignment of b‐type ΔK = ± 1 transitions, a method was developed based on the wide spectral range of the millimeter wave spectrometer. Sufficient b‐type data were obtained for CH3OH to permit a test of Kirtman's formula for origins of Q branches. Convergence difficulties in the Q‐branch least‐squares fit prompted a re‐examination of the theory, which revealed an interesting linear relation coupling six of the parameters. This relation shows that for any molec...read more
Citations
More filters
A new criterion for the determination of molecular structures from ground state rotational constants
TL;DR: In this article, it was shown that the effects of zero point vibrations are such that the coordinates obtained by substitution from the ground state moments of inertia I0 are systematically less than r0.
Journal ArticleDOI
Merck Molecular Force Field. III. Molecular Geometries and Vibrational Frequencies for MMFF94
TL;DR: In this article, the authors describe the parameterization and performance of MMFF94 for molecular geometries and deformations and demonstrate that its derivation from such data simultaneously confers the ability to reproduce experiment.
Journal ArticleDOI
Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)
Arnaud Belloche,Holger S. P. Müller,Holger S. P. Müller,Karl M. Menten,Peter Schilke,Peter Schilke,Claudia Comito +6 more
TL;DR: In this article, the authors performed an unbiased spectral line survey toward Sgr B2(N) and (M), two regions where high-mass stars are formed, with the IRAM 30 m telescope in the 3 mm atmospheric transmission window.
Journal ArticleDOI
Methanol and deuterated species: Infrared data, valence force field, rotamers, and conformation
TL;DR: In this article, a revised assignment for the species CH 3 DOH(D) and CD 3 ODH (D) is used to determine 15 significant parameters of a valence force field by a converged simultaneous least squares adjustment to 44 observed fundamentals.
Journal ArticleDOI
Models of class II methanol masers based on improved molecular data
TL;DR: In this article, the authors examined the effects on the maser models of newly available collision rate coefficients for methanol and found that at gas temperatures above 100 K the effects are broadly consistent with a reduction in the overall collision cross-section.
References
More filters
Journal ArticleDOI
The symmetry groups of non-rigid molecules
TL;DR: In this article, the concept of molecular symmetry is extended to molecules such as ethane and hydrazine, which can pass from one conformation to another, and examples are given to illustrate the use of this concept in determining the statistical weights of individual levels and selection rules for electric dipole transitions between them.
Journal ArticleDOI
Determination of Molecular Structures from Ground State Rotational Constants
TL;DR: In this article, it was shown that the effects of zero point vibrations are such that the coordinates obtained by substitution from the ground state moments of inertia I0 are systematically less than r0.
A new criterion for the determination of molecular structures from ground state rotational constants
TL;DR: In this article, it was shown that the effects of zero point vibrations are such that the coordinates obtained by substitution from the ground state moments of inertia I0 are systematically less than r0.
Journal ArticleDOI
On σ -Type Doubling and Electron Spin in the Spectra of Diatomic Molecules
TL;DR: In this paper, it was shown that the rotational distortion due to molecular rotation causes the width of a spin multiplet to depend on the position of the spin axis relative to the axis of the figure.