Tunneling splittings in the rotational spectrum of

1994 ◽  
Vol 72 (11-12) ◽  
pp. 967-970 ◽  
Author(s):  
M. Bogey ◽  
H. Bolvin ◽  
M. Cordonnier ◽  
C. Demuynck ◽  
J. L. Destombes ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Spectral Resolution ◽  
Ground State ◽  
Reasonable Agreement ◽  
Rotational Spectroscopy ◽  
Rotational Spectrum ◽  
Tunneling Splittings ◽  
Vibrational Ground State ◽  
Spectroscopy Experiment ◽  
Atom Migration

The splitting of some rotational lines due to a predicted hydrogen atom migration in protonated acetylene, [Formula: see text], was not observed in the first pure rotational spectroscopy experiment in the vibrational ground state. An improvement of the spectral resolution of the spectrometer has allowed the observation of some of these small splittings. They have been interpreted within the semi-rigid bender model. Numerical results are presented for different values of the barrier height. Reasonable agreement between observed and calculated splittings is obtained with a barrier of about 1600 cm−1, which is 15% higher than the most recent ab initio value.

scholarly journals Broad-band high-resolution rotational spectroscopy for laboratory astrophysics

2019 ◽  
Vol 626 ◽  
pp. A34 ◽  
Author(s):  
J. Cernicharo ◽  
J. D. Gallego ◽  
J. A. López-Pérez ◽  
F. Tercero ◽  
I. Tanarro ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Accurate Determination ◽  
Broad Band ◽  
Laboratory Astrophysics ◽  
High Spectral Resolution ◽  
Rotational Spectroscopy ◽  
Rotational Spectrum ◽  
Vibrationally Excited ◽  
Radio Receivers ◽  
Cold Plasmas

We present a new experimental set-up devoted to the study of gas phase molecules and processes using broad-band high spectral resolution rotational spectroscopy. A reactor chamber is equipped with radio receivers similar to those used by radio astronomers to search for molecular emission in space. The whole range of the Q (31.5–50 GHz) and W bands (72–116.5 GHz) is available for rotational spectroscopy observations. The receivers are equipped with 16 × 2.5 GHz fast Fourier transform spectrometers with a spectral resolution of 38.14 kHz allowing the simultaneous observation of the complete Q band and one-third of the W band. The whole W band can be observed in three settings in which the Q band is always observed. Species such as CH3CN, OCS, and SO2 are detected, together with many of their isotopologues and vibrationally excited states, in very short observing times. The system permits automatic overnight observations, and integration times as long as 2.4 × 105 s have been reached. The chamber is equipped with a radiofrequency source to produce cold plasmas, and with four ultraviolet lamps to study photochemical processes. Plasmas of CH4, N2, CH3CN, NH3, O2, and H2, among other species, have been generated and the molecular products easily identified by the rotational spectrum, and via mass spectrometry and optical spectroscopy. Finally, the rotational spectrum of the lowest energy conformer of CH3CH2NHCHO (N-ethylformamide), a molecule previously characterized in microwave rotational spectroscopy, has been measured up to 116.5 GHz, allowing the accurate determination of its rotational and distortion constants and its search in space.

scholarly journals Methyl Internal Rotation Fine Structure in the Ground State Rotational Spectrum of Gauche Butane

1990 ◽  
Vol 45 (8) ◽  
pp. 989-994 ◽  
Author(s):  
Kirsten Vormann ◽  
Helmut Dreizler ◽  
Hans Hübner ◽  
Wolfgang Hüttner
Keyword(s):  
Fine Structure ◽  
Internal Rotation ◽  
Barrier Height ◽  
Ground State ◽  
High Accuracy ◽  
Rotational Spectrum ◽  
Frequency Range ◽  
Vibrational Ground State ◽  
Rotation Parameters

Abstract The methyl torsional fine structure in the rotational spectrum of gauche butane in the vibrational ground state was investigated in the frequency range between 10 and 141 GHz. Using the internal axis method (IAM) in the formulation of Woods, all internal rotation parameters were determined with high accuracy. The barrier height of the methyl internal rotation was determined to 11.34 (29) kJ/mol (2.710 (69) kcal/mol)

Determination of a High Potential Barrier Hindering Internal Rotation from the Ground State Spectrum. The Methylbarrier of Ethylbromide

1985 ◽  
Vol 40 (6) ◽  
pp. 575-587 ◽  
Author(s):  
J. Gripp ◽  
H. Dreizler ◽  
R. Schwarz
Keyword(s):  
Hyperfine Structure ◽  
Internal Rotation ◽  
Potential Barrier ◽  
Ground State ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Vibrational Ground State ◽  
Distortion Analysis ◽  
High Potential Barrier

For ethylbromide a determination of the parameters of internal rotation is given derived from the rotational spectrum of the torsional and vibrational ground state. The Br-hyperfine structure is reanalysed with higher precision. As high J transitions were measured a centrifugal distortion analysis was necessary.

Rotational Spectrum of cis-HS3D

1992 ◽  
Vol 47 (10) ◽  
pp. 1091-1093 ◽  
Author(s):  
M. Liedtke ◽  
A. H. Saleck ◽  
J. Behrend ◽  
G. Winnewisser ◽  
R. Klünsch ◽  
...  
Keyword(s):  
Ground State ◽  
Rotational Spectrum ◽  
Frequency Range ◽  
Rotational Constants ◽  
Vibrational Ground State ◽  
Q 30

AbstractThe rotational spectrum of HS3D in the vibrational ground state has been measured in the frequency range between 75 and 293 GHz. Up to now, about 180 Q-, 30 P-, and 70 R-branch c-type transitions have been identified. The preliminary rotational constants of the species observed support the cis-conformation established earlier from the H2S3 rotational spectrum.

Nitrogen Quadrupole Coupling in the Rotational Spectrum of l-Isocyanoprop-2-yne, HC ≡ CCH2NC

1990 ◽  
Vol 45 (8) ◽  
pp. 986-988 ◽  
Author(s):  
M. Krüger ◽  
H. Dreizler
Keyword(s):  
Fourier Transform ◽  
Ground State ◽  
Fourier Transform Spectroscopy ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Vibrational Ground State ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Hyperfine Splittings

AbstractThe rotational spectrum of l-isocyanoprop-2-yne, HC≡CCH2NC, has been measured in the vibrational ground state by microwave Fourier transform spectroscopy from 5 to 26.5 GHz. The nuclear quadrupole hyperfine splittings due to 14N have been analysed to obtain the coupling constants χaa = 290.3(78) kHz, χbb = 10.6(80) kHz and χcc= -300.9(80) kHz

The microwave spectrum and molecular structure of trimethylene sulphoxide; bends, tilts and twists in the methylene groups

1977 ◽  
Vol 354 (1679) ◽  
pp. 491-509 ◽  
Keyword(s):  
Excited States ◽  
Ground State ◽  
Rotational Spectrum ◽  
Vibrationally Excited ◽  
Rotational Constants ◽  
Vibrational Ground State ◽  
Isotopic Species ◽  
Microwave Rotational Spectrum ◽  
Methylene Groups ◽  
The Common

The microwave rotational spectrum of the common isotopic species ( 12 CH 2 ) 32 3 S 16 O of trimethylene sulphoxide has been assigned and rotational constants obtained for the vibrational ground state, the first four excited states of the ring puckering mode and two other low-lying vibrationally excited states. In addition rotational constants have been derived for the vibrational ground state of each of the eight different singly substituted isotopic species [ 34 S], [ 13 C 2 ], [13 C 3 ], [ 2 H 2 ], [ 2 H 2 .], [ 2 H 3 ], [ 2 H 3 .] and [ 18 O], with the first three in natural abundance, and are as follows:

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