Axis Switching in the Transition of HCO: Determination of Molecular Geometry

1975 ◽  
Vol 53 (19) ◽  
pp. 2232-2241 ◽  
Author(s):  
J. M. Brown ◽  
D. A. Ramsay
Keyword(s):  
Ground State ◽  
Molecular Geometry ◽  
Spin Rotation ◽  
Resolving Power ◽  
Rotational Constants ◽  
Reliable Determination ◽  
Axis Switching ◽  
Rotation Constant ◽  
Ground State Geometry

The [Formula: see text] band systems of HCO and DCO have been reinvestigated with higher resolving power than in earlier work. Some weak lines have been assigned to K′ = 0 – K″ = 0 and K′ = 0 – K″ = 2 subbands; these lines derive their intensity from axis switching. The new data give values for the A rotational constants of HCO and DCO and permit a more reliable determination of the ground state geometry, viz, r0(CH) = 1.125(5) Å, r0(CO) = 1.175(1) Å, [Formula: see text]. The sign of the spin–rotation constant εaa has been shown to be positive.

Theoretical Determination of the Ground State Geometry of 1.3.5-Triphenylbenzene

1984 ◽  
Vol 39 (12) ◽  
pp. 1250-1254 ◽  
Author(s):  
J. Ciosłowski
Keyword(s):  
Dihedral Angle ◽  
Ground State ◽  
Reasonable Agreement ◽  
Uv Spectrum ◽  
Theoretical Determination ◽  
Transition Energies ◽  
Benzene Rings ◽  
First Ionization Potential ◽  
Ground State Geometry

The geometry and electronic structure of 1.3.5-triphenylbenzene (TPB) has been determined by semiempirical quantum methods. Using the MNDO approach, the salient dependencies of the first ionization potential, the intramolecular distances and the bond angles on the dihedral angle between the planes of the TPB benzene rings were established. By an application of the CNDO/S method the UV spectrum of TPB was calculated. A comparison of the calculated transition energies with the values observed in the absorption spectrum yields 45° for the dihedral angle, which is in reasonable agreement with the available experimental data.

Vibration-rotation bands of nitrous oxide

1951 ◽  
Vol 208 (1094) ◽  
pp. 326-331 ◽  
Keyword(s):  
Nitrous Oxide ◽  
Fine Structure ◽  
Ground State ◽  
Wave Length ◽  
The Other ◽  
Resolving Power ◽  
Microwave Measurements ◽  
Rotational Constants ◽  
Infra Red ◽  
Vibration Rotation

The infra-red absorption of nitrous oxide gas near 4·5 μ has been re-investigated using high resolving power. The rotational fine structure has been split up and shown to involve two vibrational transitions, one due to absorption of a fundamental from the ground state, and the other to a π → π transition from an excited vibrational level. The transitions have been analyzed theoretically and rotational constants obtained. The results serve to emphasize the importance of using more precise wave-length standards for infra-red measurements than have been used hitherto, if the rotational constants are to be obtained with accuracy com­parable to that achieved by microwave measurements. Excellent agreement with the latter has now been found.

Determination of the ground state rotational constants for formaldehyde: H212CO and H213CO

1979 ◽  
Vol 74 (2) ◽  
pp. 327-329 ◽  
Author(s):  
G. Winnewisser ◽  
R.A. Cornet ◽  
F.W. Birss ◽  
R.M. Gordon ◽  
D.A. Ramsay ◽  
...  
Keyword(s):  
Ground State ◽  
Rotational Constants

Internal Rotation Analysis of the Ground State Microwave Spectrum of 2-Iodopropene

1994 ◽  
Vol 49 (3) ◽  
pp. 497-502 ◽  
Author(s):  
Joachim Gripp ◽  
Helmut Dreizier
Keyword(s):  
Internal Rotation ◽  
Ground State ◽  
Microwave Spectroscopy ◽  
Microwave Spectrum ◽  
Spin Rotation ◽  
Approximate Determination ◽  
Centrifugal Distortion ◽  
Distortion Analysis ◽  
Coupling Parameters

Abstract The ground state microwave spectrum of 2-iodopropene has been reinvestigated using Fourier transform microwave spectroscopy. The barrier hindering methyl internal rotation could be ob­ tained from narrow splittings of high-J lines. In addition an improved hyperfme structure and centrifugal distortion analysis resulted in refined constants and an approximate determination of the iodine spin-rotation coupling parameters.

scholarly journals Ro-inversional Spectrum of Ammonia

1996 ◽  
Vol 51 (3) ◽  
pp. 200-206 ◽  
Author(s):  
G. Winnewisser ◽  
S. P. Belov ◽  
Th. Klaus ◽  
S. Urban
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Excellent Agreement ◽  
Ground State ◽  
Spin Rotation ◽  
Center Frequency ◽  
Line Center ◽  
Astrophysical Interest ◽  
Rotation Constant ◽  
Line Center Frequency

The ground state J = 2 ←1 , K = 0 and K = 1 ro-inversional spectrum of 14NH3 and 15NH3 at 1.2 THz has been measured with an accuracy of 20 kHz using the Cologne terahertz spectrometer. The measured frequencies for the K = 0 components are:14NH3 (J, K) = a(2, 0) - s( 1,0): 1 214 852.942(20) MHz, 15NH3 (J, K) = a(2, 0 ) - s( 1,0) : 1 210 889.556(20) MHz.In addition we have determined from saturation dip measurements of the J = 1 - 0 transition the spin-rotation constant CN = 6.7(3) kHz and the unsplit line center frequency: 14NH3 (J, K) = s( 1, 0) - a(0, 0): 572 498.163( 10) MHz. The new results are in excellent agreement with existing high resolution Fourier transform data. The terahertz line frequencies are of considerably higher accuracy than the FT-data. by about two orders of magnitude. They will serve as future calibration lines. The ro-inversional transitions are of astrophysical interest

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