The puzzling hyper-fine structure and an accurate equilibrium geometry of succinic anhydride

2020 ◽  
Vol 22 (9) ◽  
pp. 5170-5177
Author(s):  
Michaela K. Jahn ◽  
Daniel A. Obenchain ◽  
K. P. Rajappan Nair ◽  
Jens-Uwe Grabow ◽  
Natalja Vogt ◽  
...  
Keyword(s):  
Fine Structure ◽  
Succinic Anhydride ◽  
Equilibrium Geometry ◽  
Rotational Spectrum ◽  
Hyper Fine Structure

The puzzling fine structure in the rotational spectrum of succinic anhydride is explained and a semiexperimental geometry calculated.

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 Barrier Hindering Internal Rotation from the Ground State Spectrum. The Methylbarrier of Propane

1985 ◽  
Vol 40 (3) ◽  
pp. 271-273 ◽  
Author(s):  
G. Bestmann ◽  
W. Lalowski ◽  
H. Dreizler
Keyword(s):  
Fine Structure ◽  
Internal Rotation ◽  
Ground State ◽  
Methyl Groups ◽  
Rotational Spectrum ◽  
Rotation Barrier ◽  
Rotation Axes ◽  
Internal Rotation Barrier ◽  
The Moment

The internal rotation barrier V3, the moment of inertia Iα of the methyl tops and the angle between the two internal rotation axes were determined from the torsional fine structure of the rotational spectrum in the torsional ground state. A tilt angle of 1.4° of the methyl groups toward each other results.

Isotope shift and hyper fine structure in the spectrum of tin

1964 ◽  
Vol 280 (1382) ◽  
pp. 439-446 ◽  
Keyword(s):  
Fine Structure ◽  
Isotope Shift ◽  
Mass Effect ◽  
Specific Mass ◽  
Normal Mass ◽  
Configuration Mixing ◽  
Volume Shift ◽  
And Shifts ◽  
Hyper Fine Structure ◽  
Specific Mass Shift

Shifts between all the even isotopes of tin ( Z = 50) have been measured interferometrically, for enriched samples, in the line 3283 Å of the spectrum of Sn II. The h.f.s. and shifts relative to the even isotopes of two of the three odd isotopes have also been measured. The results are compared with those obtained by other workers on the tin lines 6454 and 5799 Å, (i) in order to obtain absolute values of the volume shift constant for the tin isotopes, which involves estimation of the specific mass shift in the lines, and (ii) to calculate the configuration mixing in some of the levels concerned. After allowing for normal mass effect only the measured shifts are: 112-114; 22.0 mK; 114-116, 21.9 mK; 116-118, 18.0 mK; 118-120, 18.4 mK; 120-122, 16.6 mK; 122-124, 11.7 mK; 116-117, 8.4 mK; 118-119, 2.4 mK. A hyperfine doublet was observed in 3283 Å for both 117 Sn and 119 Sn; the splittings are 153.6 and 162.3 mK respectively and are attributed to the lower level involved in the transition.

scholarly journals Isolation of a Halogen-Bonded Complex Formed between Methane and Chlorine Monofluoride and Characterisation by Rotational Spectroscopy and Ab Initio Calculations

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4257 ◽  
Author(s):  
Anthony C. Legon ◽  
David G. Lister ◽  
John H. Holloway ◽  
Devendra Mani ◽  
Elangannan Arunan
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Internal Rotation ◽  
Halogen Bond ◽  
Spectroscopic Constants ◽  
Bond Critical Point ◽  
Equilibrium Geometry ◽  
Rotational Spectrum ◽  
Pulsed Jet ◽  
Explicitly Correlated

A halogen-bonded complex formed between methane and chlorine monofluoride has been isolated in the gas phase before the reaction between the components and has been characterised through its rotational spectrum, which is of the symmetric-top type but only exhibits K = 0 type transitions at the low effective temperature of the pulsed-jet experiment. Spectroscopic constants for two low-lying states that result from internal rotation of the CH4 subunit were detected for each of the two isotopic varieties H4C···35ClF and H4C···37ClF and were analysed to show that ClF lies on the symmetry axis with Cl located closer than F to the C atom, at the distance r0(C···Cl) ≅ 3.28 Å and with an intermolecular stretching force constant kσ ≅ 4 N m−1. Ab initio calculations at the explicitly correlated level CCSD(T)(F12c)/cc-pVTZ-F12 show that in the equilibrium geometry, the ClF molecule lies along a C3 axis of CH4 and Cl is involved in a halogen bond. The Cl atom points at the nucleophilic region identified on the C3 axis, opposite the unique C–H bond and somewhere near the C atom and the tetrahedron face centre, with re(C···Cl) = 3.191 Å. Atoms-in-molecules (AIM) theory shows a bond critical point between Cl and C, confirming the presence of a halogen bond. The energy that is required to dissociate the complex from the equilibrium conformation into its CH4 and ClF components is only De ≅ 5 kJ mol−1. A likely path for the internal rotation of the CH4 subunit is identified by calculations at the same level of theory, which also provide the variation of the energy of the system as a function of the motion along that path. The barrier to the motion along the path is only ≅ 20 cm−1.

Rotational spectrum of silyl chloride: hyperfine structure and equilibrium geometry

2012 ◽  
Vol 110 (19-20) ◽  
pp. 2359-2369 ◽  
Author(s):  
Gabriele Cazzoli ◽  
Cristina Puzzarini ◽  
Jürgen Gauss
Keyword(s):  
Hyperfine Structure ◽  
Equilibrium Geometry ◽  
Rotational Spectrum
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