Infrared – Radio-frequency Double Resonance Observations of Δ J = 0 ‘Forbidden’ Rotational Transitions of SiH4

1975 ◽  
Vol 53 (19) ◽  
pp. 2000-2006 ◽  
Author(s):  
W. A. Kreiner ◽  
T. Oka
Keyword(s):  
Radio Frequency ◽  
Double Resonance ◽  
Laser Cavity ◽  
Infrared Laser ◽  
Microwave Spectrum ◽  
Centrifugal Distortion ◽  
Fundamental Band ◽  
Rotational Transitions ◽  
Centrifugal Distortion Constants

The radio-frequency and microwave spectrum of SiH4 corresponding to ΔJ = 0 ‘forbidden’ rotational transitions between the centrifugal distortion multiplets of levels has been studied by using the method of infrared–microwave double resonance in a laser cavity. Coincidences between the v4 fundamental band of SiH4 and N2O infrared laser lines in the 10 μm region have been used. Seven double resonance signals have been found and four of them were assigned to the J = 5, and J = 9 'forbidden' rotational transitions. From the measured frequencies, the quartic and sextic centrifugal distortion constants were determined as D1 = 74 861 ± 15 Hz, H4t = −7.14 ± 0.3 Hz, and H6t = 6.57 ± 1.1 Hz.

Microwave Spectrum of Methane-d2, CH2D2

1975 ◽  
Vol 53 (19) ◽  
pp. 2023-2028 ◽  
Author(s):  
Eizi Hirota ◽  
Misako Imachi
Keyword(s):  
Dipole Moment ◽  
Microwave Spectrum ◽  
Normal Coordinate Analysis ◽  
Centrifugal Distortion ◽  
Normal Coordinate ◽  
Rotational Constants ◽  
Microwave Spectrometer ◽  
Rotational Transitions ◽  
Centrifugal Distortion Constants

Three rotational transitions of methane-d2 were observed by a source-modulation microwave spectrometer. The two differences in the rotational constants, A – C and B – C, were determined to be 37 555.758 and 13 664.280 MHz, respectively, from the observed frequencies of 110 ← 101 and 211 ← 202 after correcting for the centrifugal distortion effects. The centrifugal distortion constants were evaluated by a normal coordinate analysis. The dipole moment of CH2D2 was determined to be 0.014 ± 0.005 D, by comparing the intensity of 211 ← 202 with that of an oxygen line.

Pure rotational spectrum of 13CD4 and isotope effects on the tensorial centrifugal-distortion constants of methane

1987 ◽  
Vol 65 (1) ◽  
pp. 32-37 ◽  
Author(s):  
W. A. Kreiner ◽  
P. Müller ◽  
L. Jörissen ◽  
M. Oldani ◽  
A. Bauder
Keyword(s):  
Fourier Transform ◽  
Radio Frequency ◽  
Ground State ◽  
Isotope Effects ◽  
Double Resonance ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Theoretical Predictions ◽  
Deuterium Isotope Effects ◽  
Centrifugal Distortion Constants

Infrared-laser – radio-frequency double-resonance experiments and pulsed-microwave Fourier-transform measurements have been performed with 13CD4. From 25 observed ΔJ = 0 transitions in the vibronic ground state, the tensorial centrifugal-distortion constants Dt = 32.6600(12) kHz, H4t = −2.0302(61) Hz, H6t = 1.1692(29) Hz, L4t = 1.201(77) × 10−4 Hz, L6t = −1.353(63) × 10−4 Hz, and L8t = −1.466(46) × 10−4 Hz have been determined. Experimental carbon-13 and deuterium isotope effects on the tensorial centrifugal-distortion constants of methane have been compared with theoretical predictions.

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 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

Microwave spectrum, dipole moment, and centrifugal distortion constants of 1,2,3,5-tetrafluorobenzene

1977 ◽  
Vol 55 (14) ◽  
pp. 1211-1217 ◽  
Author(s):  
S. D. Sharma ◽  
S. Doraiswamy
Keyword(s):  
Dipole Moment ◽  
Bond Length ◽  
Benzene Ring ◽  
Microwave Spectrum ◽  
Frequency Region ◽  
Centrifugal Distortion ◽  
Dry Ice ◽  
Type Spectrum ◽  
Centrifugal Distortion Constants

The microwave spectrum of 1,2,3,5-tetrafluorobenzene has been studied at dry ice temperature in the frequency region of 8 to 12.4 GHz. The molecule is highly asymmetric (κ = 0.001129) and exhibits an a-type spectrum. The analysis of the spectrum has been carried out to obtain the following Watson's eight determinable parameters: [Formula: see text], [Formula: see text], [Formula: see text], τ′aaaa = −1.30 ± 1.26 kHz, τ′bbbb = −4.05 ± 0.40 kHz, τ′cccc = −0.75 ± 0.40 kHz, τ1 = −15.21 ± 1.34 kHz and [Formula: see text]. The dipole moment of the molecule is found to be 1.46 ± 0.06 D. The calculated values obtained from INDO and CNDO approximations are 1.73 and 1.64 D, respectively. The benzene ring appears to have undergone a distortion if we assume that C(sp2)—F bond length is around 135 pm.

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