The microwave spectrum of the OH X2Π radical in the ground and vibrationally-excited (ν ≤ 6) levels

1979 ◽  
Vol 57 (5) ◽  
pp. 619-634 ◽  
Author(s):  
J. A. Coxon ◽  
K. V. L. N. Sastry ◽  
J. A. Austin ◽  
D. H. Levy
Keyword(s):  
Absorption Spectrum ◽  
Parallel Plate ◽  
Microwave Spectrum ◽  
Hamiltonian Matrix ◽  
Centrifugal Distortion ◽  
Linear Least Squares ◽  
Vibrationally Excited ◽  
Hyperfine Constants ◽  
Vibrational Levels ◽  
Astrophysical Significance

The microwave absorption spectrum of the OH X2Π radical has been observed in all vibrational levels up to ν = 6. Experimental details are described of the tunable cavity and parallel plate Stark-modulated spectrometers employed for transitions below and above 23 GHz, respectively. The observed line frequencies, together with those reported by other workers, have been fitted using a non-linear least-squares routine with numerical diagonalization of the Hamiltonian matrix. Pseudo high-order corrections for centrifugal distortion of the Λ-doubling are required for the ν = 0 data, which now extend to J = 19/2 in the 2Π1/2 component. The various adjustable parameters of the Hamiltonian are compared with those of other similar models. The Λ-doubling and magnetic hyperfine constants for the different vibrational levels are reported, and several line frequencies of potential astrophysical significance are predicted.

A Contribution to the Microwave Spectrum of 1,2-Difluoroethane

1981 ◽  
Vol 36 (11) ◽  
pp. 1239-1241
Author(s):  
H. Dreizier ◽  
D. Steffek
Keyword(s):  
Excited States ◽  
Microwave Spectrum ◽  
Centrifugal Distortion ◽  
Vibrationally Excited ◽  
Distortion Analysis

The microwave spectrum of gauche 1,2-difluoroethane w as investigated in the ground and five vibrationally excited states by a centrifugal distortion analysis.

scholarly journals Microwave Spectrum and Quadrupole Coupling Constants of 2-Chlorothiophene

1973 ◽  
Vol 28 (5) ◽  
pp. 729-738 ◽  
Author(s):  
J. Mjöberg ◽  
S. Ljunggren
Keyword(s):  
Ground State ◽  
Hyperfine Splitting ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Centrifugal Distortion ◽  
Vibrationally Excited ◽  
Isotopic Species ◽  
Principal Axes ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

The microwave spectra of the two chlorine isotopic species of 2-chlorothiophene have been measured in the region 26 500 - 40 000 MHz.For both isotopic species, the rotational constants of the ground state and one vibrationally excited state were determined, as well as the centrifugal distortion coefficients of the ground state.From the hyperfine splitting of the rotational lines, the nuclear quadrupole coupling constants were calculated. The values in MHz are for 35Cl:and for 37Cl: χaa= -74.77 ±0.05, χbb=37.51 ± 0.17, χcc=37.25 ± 0.18 χaa= -58.98 ±0.09, χbb=29.55 ± 0.26, χcc=29.43 ± 0.28in the principal-axes system of the molecule.

The Microwave Spectrum of Isopropyl Iodide: The Iodine Hyperfine Structure and a Centrifugal Distortion Analysis

1990 ◽  
Vol 45 (5) ◽  
pp. 715-723 ◽  
Author(s):  
Joachim Gripp ◽  
Helmut Dreizler
Keyword(s):  
Double Resonance ◽  
Rotational Constant ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Hamiltonian Matrix ◽  
Centrifugal Distortion ◽  
Frequency Range ◽  
Least Squares Fit ◽  
Distortion Analysis ◽  
Centrifugal Distortion Constants

Abstract The ground stafe microwave spectrum of isopropyl iodide has been investigated by microwave Fourier transform (MWFT) spectroscopy. 212 hyperfine components of 39 mainly a-type transitions have been assigned from the measured spectra in the frequency range between 4 and 30 GHz. With a MWFT double resonance modulation (MWFTDR) spectrometer a weak c-type transition and a "forbidden" ΔJ = 2 line could be observed. The spectra were analysed using a diagonalization procedure of the complete Hamiltonian matrix and a simultaneous least squares fit of the rotational, quartic centrifugal distortion and the iodine quadrupole and spin rotation coupling constants directly to the measured frequencies. A set of 14 constants could be obtained with high accuracy. The rotational constant A and some of the centrifugal distortion constants could be improved using some large higher order quadrupole perturbations and the results of the MWFTDR measurements for the analysis.

Microwave Spectrum of 1-Butene Oxide

1978 ◽  
Vol 33 (11) ◽  
pp. 1312-1322
Author(s):  
S. O. Ljunggren ◽  
P. J. Mjöberg ◽  
J . E. Bäckvall
Keyword(s):  
Dipole Moment ◽  
Gas Phase ◽  
Internal Rotation ◽  
Barrier Height ◽  
Excited States ◽  
Ground State ◽  
Microwave Spectrum ◽  
Frequency Region ◽  
Centrifugal Distortion ◽  
Vibrationally Excited

The microwave spectrum of 1-butene oxide in the gas phase has been studied in the frequency region 18.0-39.0 GHz. The spectrum observed arose from a rotamer with a dihedral H-C2-C3-C4 angle of 59° ± 1°. In addition to several Q-branch progressions the spectrum contained several long perpendicular RP and PR progressions. However, of the ground state lines, only the intermediate PR transitions showed internal rotation splittings that could be resolved to yield a barrier height of 3.02 kcal mol-1. The value derived from the line splittings of the first excited methyl torsional state was slightly higher (3.17 kcal mol-1) but must be regarded as being less reliable. The components of the dipole moment, the rotational constants, and the quartic and sextic centrifugal distortion coefficients for the ground state and three vibrationally excited states were determined.

ChemInform Abstract: MICROWAVE SPECTRUM OF PROPIONITRILE. DETERMINATION OF THE QUARTIC AND SEXTIC CENTRIFUGAL DISTORTION CONSTANTS

1978 ◽  
Vol 9 (51) ◽  
Author(s):  
J. BURIE ◽  
J. DEMAISON ◽  
A. DUBRULLE ◽  
D. BOUCHER
Keyword(s):  
Microwave Spectrum ◽  
Centrifugal Distortion ◽  
Centrifugal Distortion Constants

scholarly journals The Microwave Spectrum of 3,4-Dihydro-1,2-Pyran

1985 ◽  
Vol 40 (9) ◽  
pp. 913-919
Author(s):  
Juan Carlos López ◽  
José L. Alonso
Keyword(s):  
Dipole Moment ◽  
Excited States ◽  
Ground State ◽  
Principal Axis ◽  
Microwave Spectrum ◽  
Average Intensity ◽  
Ring Conformation ◽  
Vibrationally Excited ◽  
Rotational Constants ◽  
Displacement Measurements

Abstract The rotational transitions of 3,4-dihydro-1,2-pyran in the ground state and six vibrationally excited states have been assigned. The rotational constants for the ground state (A = 5198.1847(24), B = 4747.8716(24) and C = 2710.9161(24) have been derived by fitting μa, μb and μc-type transitions. The dipole moment was determined from Stark displacement measurements to be 1.400(8) D with its principal axis components |μa| =1.240(2), |μb| = 0.588(10) and |μc| = 0.278(8) D. A model calculation to reproduce the ground state rotational constants indicates that the data are consistent with a twisted ring conformation. The average intensity ratio gives vibrational separations between the ground and excited states of the ring-bending and ring-twisting modes of ~ 178 and ~ 277 cm-1 respectively.

Molecules in strong laser fields: vibrational inversion and harmonic generation

1994 ◽  
Vol 72 (3) ◽  
pp. 673-677 ◽  
Author(s):  
Eric E. Aubanel ◽  
André D. Bandrauk
Keyword(s):  
Harmonic Generation ◽  
Laser Pulses ◽  
Harmonic Spectrum ◽  
Femtosecond Laser Pulses ◽  
Generation Process ◽  
High Order Harmonic Generation ◽  
Vibrationally Excited ◽  
Potential Wells ◽  
High Order Harmonic ◽  
Vibrational Levels

We examine two consequences of the unique behaviour of molecules in strong fields. First, by time gating of laser-induced avoided crossings with femtosecond laser pulses, one can obtain efficient vibrational inversion into a narrow distribution of vibrational levels of a molecular ion. We demonstrate this by numerical solution of the time-dependent Schrödinger equation for [Formula: see text] Second, we show results of numerical calculation with vibrationally excited [Formula: see text] of harmonic generation up to the 11th order of an intense 1064- nm laser. We predict that competition of photodissociation can be minimized by trapping the molecule in high-field-induced potential wells, thus enhancing the high-order harmonic generation process. Furthermore, the harmonic spectrum can serve as a measure of the structure of these laser-induced potentials.

scholarly journals Subauroral red arcs as a conjugate phenomenon: comparison of OV1-10 satellite data with numerical calculations

1997 ◽  
Vol 15 (8) ◽  
pp. 984-998 ◽  
Author(s):  
A. V. Pavlov
Keyword(s):  
Electron Density ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Atomic Oxygen ◽  
Major Ions ◽  
Integral Intensity ◽  
Rate Coefficients ◽  
Vibrationally Excited ◽  
Vibrational Distribution ◽  
Vibrational Levels

Abstract. This study compares the OV1-10 satellite measurements of the integral airglow intensities at 630 nm in the SAR arc regions observed in the northern and southern hemisphere as a conjugate phenomenon, with the model results obtained using the time-dependent one-dimensional mathematical model of the Earth ionosphere and plasmasphere (the IZMIRAN model) during the geomagnetic storm of the period 15–17 February 1967. The major enhancements to the IZMIRAN model developed in this study are the inclusion of He+ ions (three major ions: O+, H+, and He+, and three ion temperatures), the updated photochemistry and energy balance equations for ions and electrons, the diffusion of NO+ and O2+ ions and O(1D) and the revised electron cooling rates arising from their collisions with unexcited N2, O2 molecules and N2 molecules at the first vibrational level. The updated model includes the option to use the models of the Boltzmann or non-Boltzmann distributions of vibrationally excited molecular nitrogen. Deviations from the Boltzmann distribution for the first five vibrational levels of N2 were calculated. The calculated distribution is highly non-Boltzmann at vibrational levels v > 2 and leads to a decrease in the calculated electron density and integral intensity at 630 nm in the northern and southern hemispheres in comparison with the electron density and integral intensity calculated using the Boltzmann vibrational distribution of N2. It is found that the intensity at 630 nm is very sensitive to the oxygen number densities. Good agreement between the modelled and measured intensities is obtained provided that at all altitudes of the southern hemisphere a reduction of about factor 1.35 in MSIS-86 atomic oxygen densities is included in the IZMIRAN model with the non-Boltzmann vibrational distribution of N2. The effect of using of the O(1D) diffusion results in the decrease of 4–6% in the calculated integral intensity of the northern hemisphere and 7–13% in the calculated integral intensity of the southern hemisphere. It is found that the modelled intensities of the southern hemisphere are more sensitive to the assumed values of the rate coefficients of O+(4S) ions with the vibrationally excited nitrogen molecules and quenching of O+(2D) by atomic oxygen than the modelled intensities of the northern hemisphere.

Microwave spectrum and centrifugal distortion constants of morpholine

1979 ◽  
Vol 78 (1) ◽  
pp. 175-180 ◽  
Author(s):  
Roberto R. Filgueira ◽  
Adolfo C. Fantoni ◽  
Luis M. Boggia
Keyword(s):  
Microwave Spectrum ◽  
Centrifugal Distortion ◽  
Centrifugal Distortion Constants
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