scholarly journals Microwave Spectra of Furazan. III. Rotation Spectra of Vibrationally Excited States

1990 ◽  
Vol 45 (9-10) ◽  
pp. 1117-1130
Author(s):  
Otto L. Stiefvater
Keyword(s):  
Excited States ◽  
Heterocyclic Compound ◽  
Microwave Spectroscopy ◽  
Vibrational Modes ◽  
Vibrationally Excited ◽  
Rotational Constants ◽  
Rotational Spectra ◽  
Microwave Spectra

Abstract The pure rotational spectra of molecules in 21 vibrationally excited states of the heterocyclic compound furazan (C2H2N2O) have been detected and studied by DRM microwave spectroscopy. Rotational parameters are reported for the 12 fundamental levels below 1500 cm-1 , and the contri-butions from 10 vibrational modes to the effective rotational constants and to the inertia defect of furazan are calculated.

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.

scholarly journals Microwave Spectra of Dimethylether (CH3)2O and (CD3)2O in Excited Torsional States

1978 ◽  
Vol 33 (12) ◽  
pp. 1498-1510 ◽  
Author(s):  
H. Lutz ◽  
H. Dreizler
Keyword(s):  
Fine Structure ◽  
Excited States ◽  
Rotational Spectra ◽  
Microwave Spectra

Abstract The rotational spectra of the torsional excited states v̅n = 11,12,21, 22, 23 have been measured and assigned. The torsional fine structure was used to determine the coefficients V3 and V' 12 of the hindering potential. For (CH3)2O : V3 = 2618 ± 4 cal/mole, V'12 = 18 ± 8 cal/mole, for (CD3)2O : V3 = 2572 ± 6 cal/mole, V'12 = 29 ± 12 cal/mole, V12 was correlated to V3 .

Preferred Rotameric Conformations of Isobutyraldehyde, Their Dipole Moments and Vibrationally Excited States by Microwave Spectroscopy

1986 ◽  
Vol 41 (3) ◽  
pp. 483-490 ◽  
Author(s):  
O. L. Stiefvater
Keyword(s):  
Oxygen Atom ◽  
Excited States ◽  
Ground State ◽  
Dipole Moments ◽  
Microwave Spectroscopy ◽  
Centrifugal Distortion ◽  
Gauche Conformation ◽  
Vibrationally Excited ◽  
Trans Conformation ◽  
Centrifugal Distortion Constants

The earlier prediction of the preferred and the less stable rotameric conformations of isobutyraldehyde, (CH3)2CHCHO, has been confirmed experimentally by microwave spectroscopy. The compound exists mainly in a gauche conformation, in which one of the methyl groups is eclipsed by the oxygen atom, and the less stable rotamer is the trans conformation, in which the oxygen atom eclipses the isopropyl hydrogen.Ground state rotational constants (in MHz) and centrifugal distortion constants (in kHz), together with dipole moments (in D), are:Rotation spectra due to three torsionally excited states of each rotamer have been identified, along with satellites arising from CH3 internal rotation and CC2 wagging.

scholarly journals Microwave Spectrum and Nuclear Quadrupole Interaction of 3-Bromothiophene in Excited Vibrational States

1983 ◽  
Vol 38 (12) ◽  
pp. 1309-1319 ◽  
Author(s):  
Yoshiaki Sasada
Keyword(s):  
Excited States ◽  
Nuclear Quadrupole Interaction ◽  
Coupling Constants ◽  
Vibrational Modes ◽  
Centrifugal Distortion ◽  
Vibrational States ◽  
Rotational Spectra ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Centrifugal Distortion Constants

Abstract The rotational spectra of 3-bromothiophene in the excited states of two vibrational modes were observed and the rotational constants, the centrifugal distortion constants, and the nuclear quadrupole coupling constants were determined. The wave numbers of the two vibrational modes were evaluated to be 210 cm-1 and 320 cm-1 by measuring relative intensities of the ground and excited vibrational transitions. Variations in the inertia defect for each of the vibrational modes are compared with the results of the approximate calculation.

Microwave Spectrum of Acetyl Cyanide in the Ground and Excited States. I

1976 ◽  
Vol 31 (7) ◽  
pp. 840-846
Author(s):  
F. Scappini ◽  
H. Dreizler
Keyword(s):  
Internal Rotation ◽  
Excited States ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Rotational Constants ◽  
Microwave Spectra ◽  
Torsion Vibration ◽  
Quadrupole Coupling ◽  
Rotation Parameters

Abstract The microwave spectra of acetyl cyanide, CH3COCN, in the ground and in the two lowest excited states have been investigated. The rotational constants and the quadrupole coupling constants have been evaluated for all these states. The internal rotation parameters have been refined with respect to previous works. Evidence for a rotation-torsion -vibration interaction has been found in the spectra of the excited states.

Etude à basse température dans l'infrarouge proche du dimère (NO)2

1984 ◽  
Vol 62 (4) ◽  
pp. 322-329 ◽  
Author(s):  
V. Menoux ◽  
R. Le Doucen ◽  
C. Haeusler ◽  
J. C. Deroche
Keyword(s):  
Excited State ◽  
Gas Phase ◽  
Ground State ◽  
Near Infrared ◽  
Heat Of Formation ◽  
Wave Number ◽  
Vibrational Modes ◽  
Vibrationally Excited ◽  
Rotational Constants ◽  
Absorption Intensity

The spectrum of the dimer (NO)2 in the gas phase has been studied in the near infrared at temperatures between 118 and 138 K. More specifically, the measure of absorption intensity of the ν4 and ν1 + ν4 bands has yielded the heat of formation of the dimer, −2.25 kcal/mol at 128 K, and revealed the influence of the low vibrational modes on this measure. The observation of the ν4 – ν6, difference band has yielded the wave number value of the ν6, fundamental band, forbidden in the infrared. The rotational constants of the vibrationally excited state were found to be larger than the ground state rotational constants, this result being very unusual.

Microwave spectroscopy of furfural in vibrationally excited states

2007 ◽  
Vol 244 (1) ◽  
pp. 9-12 ◽  
Author(s):  
R.A. Motiyenko ◽  
E.A. Alekseev ◽  
S.F. Dyubko
Keyword(s):  
Excited States ◽  
Microwave Spectroscopy ◽  
Vibrationally Excited

High-Resolution Vibrational Spectra of Furazan

1991 ◽  
Vol 46 (10) ◽  
pp. 841-850
Author(s):  
Otto L. Stiefvater
Keyword(s):  
Excited States ◽  
Ground State ◽  
Double Resonance ◽  
Microwave Spectroscopy ◽  
Statistical Uncertainty ◽  
Molecular Constants ◽  
Vibrationally Excited ◽  
Vibrational Ground State ◽  
Vibrational Bands ◽  
Ft Ir

AbstractThe study by Fourier transform (FT) infrared (IR) spectroscopy of the fundamental vibrational bands v12 and v5 of furazan yields the origins of these bands with a statistical uncertainty of 10-6 cm-1, which leads to an estimated absolute uncertainty of 10-4 cm-1. The values are v°12 = 952.6123 cm -1 and v°5 = 1.005.3536 cm -1. They confirm the values previously deduced from laser/microwave double resonance (LMDR) experiments. Previous results for the molecular constants of the vibrational ground state and of the two vibrationally excited states, as obtained by double resonance modulation (DRM) microwave spectroscopy alone, are confirmed and refined. Advantages brought about through the combination of the DRM microwave and the FT-IR technique are outlined.

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