Zum Mikrowellenspektrum des Pyridazins

1967 ◽  
Vol 22 (4) ◽  
pp. 531-543 ◽  
Author(s):  
W. Werner ◽  
H. Dreizler ◽  
H. D. Rudolph
Keyword(s):  
Ground State ◽  
Stark Effect ◽  
Coupling Constants ◽  
Isotopic Substitution ◽  
Rotational Spectrum ◽  
Coupling Tensor ◽  
Vibrational Ground State ◽  
Principal Axes ◽  
Quadrupole Coupling ◽  
Tensor Element

The rotational spectrum of pyridazine in the vibrational ground state is reported for the parent species and three isotopically substituted species. The rs coordinates of the ring atoms have been reliably determined with the exception of the α coordinate of the Cl and the C4 atoms which is obviously too small for the application of KRAITCHMAN’S equations. The dipole moment was calculated from the STARK effect as μα=4.22 D. The quadrupole coupling constants, from hfs measurements, are χαα=— 4.64, χbb=1.38, χcc=3.27 MHz. The only non-diagonal quadrupole coupling tensor element has been less accurately determined from the variation of the hfs upon rotation of the principal axes system by isotopic substitution of one N15 nucleus.

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

11Boron Quadrupole Hyperfine Structure in the Rotational Spectrum of Hydroxydifluoroborane

1989 ◽  
Vol 44 (12) ◽  
pp. 1191-1195 ◽  
Author(s):  
Kirsten Vormann ◽  
Helmut Dreizler
Keyword(s):  
Hyperfine Structure ◽  
Diagonal Element ◽  
Coupling Constants ◽  
Isotopic Substitution ◽  
Rotational Spectrum ◽  
Rotational Spectra ◽  
Coupling Tensor ◽  
Isotopic Species ◽  
Quadrupole Coupling

Abstract The 11B quadrupole hyperfine structure in the rotational spectra of three isotopic species of hydroxydifluoroborane, BF2OH, BF2OD, and BF218OH has been investigated and the quadrupole coupling constants of these species have been determined. Using the variation of the 11B quadrupole coupling constants with isotopic substitution, it has been possible to evaluate the complete quadrupole coupling tensor, including the off-diagonal element %ab, for each isotopic species.

Investigation of the Microwave Spectrum of Cyclopropyl Isocyanate. An Example for the Failure of Centrifugal Distortion Theory

1990 ◽  
Vol 45 (9-10) ◽  
pp. 1175-1184 ◽  
Author(s):  
C. Heldmann ◽  
H. Dreizler
Keyword(s):  
Fourier Transform ◽  
Hyperfine Structure ◽  
Ground State ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Vibrational Ground State ◽  
Quadrupole Coupling

Abstract The vibrational ground state microwave spectrum of cyclopropyl isocyanate was investigated in the region from 8.4 to 40 GHz by microwave Fourier transform (MWFT) spectroscopy. The quadru-pole hyperfine structure was resolved and assigned. The quadrupole coupling constants are given. With respect to the data given in the literature up to now, this work led to a more profound description of the pure rotational spectrum. Furthermore, some interesting and surprising results concerning the effect of centrifugal distortion are presented. Compared to hitherto existing investi-gations, these results indicate a more complicated conformational behaviour of cyclopropyl iso-cyanate.

Molecular Structure, Quadrupole Coupling Tensor and Dipole Moment of Ethyl Cyanide

1974 ◽  
Vol 29 (9) ◽  
pp. 1345-1355 ◽  
Author(s):  
H. M. Heise ◽  
H. Lutz ◽  
H. Dreizler
Keyword(s):  
Dipole Moment ◽  
Stark Effect ◽  
Principal Axis ◽  
Coupling Constants ◽  
Coupling Tensor ◽  
Principal Axes ◽  
Quadrupole Coupling ◽  
Principal Axis System ◽  
Structure Calculations ◽  
Good Agreement

The microwave spectra of CD3CH2CN, 13CH3CH2CN, CH313CH2CN and CH3CH2C15N have been measured. In addition the spectrum of CH3CH213CN has been remeasured with greater accuracy. From these spectra and those previously reported - CH3CH2CN, CH3CD2CN, CH2DCH2CN (sym) and CH2DCH2CN (asym) - a complete rs-structure has been calculated by the equations of Kraitchman and Chutjian. r0-structure calculations were performed with different assumptions due to the symmetry of the molecule. A comparison between r0- and rs-structure was made and showed good agreement especially for the atoms of the frame.The quadrupole coupling constants of the above mentioned isotopes of ethyl cyanide were obtained from the hyperfine structure of the spectra with the exception of CH3CH2C15N, which has no nucleus with quadrupole moment. The quadrupole coupling tensor in its principal axis system was determined from the constants of CD3CH2CN and CH3CD2CN using the angle e between their principal axes of inertia in the a-b-plane.From Stark effect measurements the dipole moment of CH3CH2CN was reevaluated. To determine the direction of the dipole moment Stark effect measurements for CD3CH2CN and CH3CD2CN were carried out.

Microwave Spectrum and Quadrupole Coupling Constants of Orthochloropyridine

1972 ◽  
Vol 27 (6) ◽  
pp. 1011-1014 ◽  
Author(s):  
F Scappini ◽  
A Guarnieri
Keyword(s):  
Ground State ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Rotational Constants ◽  
Vibrational Ground State ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

Abstract The rotational spectrum of 2-chloropyridine was measured in the region between 8-40 GHz. The rotational constants for the vibrational ground state are: A = 5872.01 ± 0.02 MHz, B = 1637.82 ± 0.02 MHz, C=1280.51 ± 0.02 MHz. The value 0.0385 amu · A2 of the inertia defect indicates a planar nuclear frame. From the hyper-fine splittings of the rotational lines the nuclear quadrupole coupling constants of 35Cl were determined. The values are:χaa = 70.79 ± 0.17 MHz, χbb = 39.01 ± 0.45 MHz, χcc = 31.78 ± 0.62 MHz.

scholarly journals Microwave Spectrum and Quadrupole Coupling Constants of 2-Bromothiophene

1975 ◽  
Vol 30 (4) ◽  
pp. 541-548 ◽  
Author(s):  
P. J. Mjöberg ◽  
W. M. Ralowski ◽  
S. O. Ljunggren
Keyword(s):  
Ground State ◽  
Second Order ◽  
Coupling Constants ◽  
Order Perturbation ◽  
Vibrationally Excited ◽  
Rotational Constants ◽  
Isotopic Species ◽  
Principal Axes ◽  
Quadrupole Coupling ◽  
Hyperfine Splittings

Abstract The microwave spectra of the two 79Br and 81Br isotopic species of 2-bromothiophene have been measured in the region 18000-40000 MHz.For both isotopic species, the rotational constants of the ground state and one vibrationally excited state were determined, as well as the centrifugal distortion coefficients of the ground state. The ground state rotational constants in MHz are as follows:C4H332S79Br C4H332S81BrA = 5403.432 ±0.111 5403.563 ±0.095,B = 1139.0689±0.0010 1126.5173±0.0011 C = 940.5142±0.0018 931.9315±0.0009.In order to perform a second-order perturbation treatment of the quadrupole interaction, the matrix elements of products of direction cosines in terms of the symmetric top wave functions have been derived. By the first-and second-order perturbation analysis of the hyperfine splittings of the rotational lines, the nuclear quadrupole coupling constants have been determined. The values in MHz areXaa = 592.7 ±1.5 493.7 ±1.5,Xbb = -295.3 ±0.6 -245.6 ±0.7, Xcc = -297.4 ±1.6 -248.1 ±1.6,Xab = 80 ±9 64±8 ,in the principal axes system of the molecule.

ab initio Calculation of 33S Quadrupole Coupling Constants. Reanalysis of the 33S Hyperfine Structure in the Rotational Spectrum of Thiirane

1997 ◽  
Vol 52 (4) ◽  
pp. 297-305 ◽  
Author(s):  
Barbara Kirchner ◽  
Hanspeter Huber ◽  
Gerold Steinebrunner ◽  
Helmut Dreizler ◽  
Jens-Uwe Grabow ◽  
...  
Keyword(s):  
Ab Initio Calculation ◽  
Experimental Information ◽  
Coupling Constants ◽  
Basis Sets ◽  
Rotational Spectrum ◽  
Rotational Spectra ◽  
Coupling Tensor ◽  
Quadrupole Coupling ◽  
Local Quality ◽  
Nuclear Quadrupole

Abstract We present quantum chemical calculations on the MP4(SDQ) level with basis sets of high local quality to determine the nuclear quadrupole coupling tensor of 33S in a series of molecules, which were investigated up to now by microwave spectroscopy. The analysis of the nuclear quadrupole coupling in the rotational spectra provided experimental information on the tensors. As an example for such an analysis, improved values for thiirane, C2H433S, are given: χaa = - 32.9425(78) MHz, χbb = -16.402(14) MHz, χcc = 49.345(14) MHz.

Mikrowellenspektrum, Struktur und l-Typ-Dublett-Aufspaltung der HCNO (Knallsäure)

1967 ◽  
Vol 22 (11) ◽  
pp. 1724-1737 ◽  
Author(s):  
Manfred Winnewisser ◽  
Hans Karl Bodenseh
Keyword(s):  
Ground State ◽  
Stark Effect ◽  
Coupling Constants ◽  
Vibrational Modes ◽  
Quadrupole Coupling ◽  
Bending Modes ◽  
First Time ◽  
O 11 ◽  
O 10 ◽  
Marked Dependence

The microwave spectra of unstable, gaseous fulminic acid H12C14N16O and five of its isotopically substituted species have been studied in the frequency range from 10 to 46 GHz. The spectrum of molecules in the ground vibrational state established the linearity of the chain HCNO. The following rotational constants B0 for the ground state were obtained:B0 (H12C14N16O) = 11 469.04 MHz, B0 (H12C14N17O) = 11 151.69 MHz,B0 (D12C14N16O) = 10 292.51 MHz, B0 (H12C14N18O) = 10 865.34 MHz,B0 (H13C14N16O) = 11 091.57 MHz, B0 (D13C14N16O) = 10 011.18 MHz.From these a combined r8- and r0-structure has been evaluated: r(C—H) = (1.027±0.001) A, r(C—N) = (1.161 ± 0.015) A, r(N—O) = (1.207±0.015) A.The rather large uncertainties in the C—N- and N—O-distances are due to the proximity of the N-atom to the center of gravity.It appears to be the first time that, in the same molecule, two different ι-type doublets (Δl=0, AJ= + 1) and their corresponding series of /-type doubling transitions (Al =2, ΔJ = 0), arising from the two degenerate bending modes (υ4=1 and v5=1), have been observed.The analysis of the two ι-type doubling series revealed a marked dependence of the /-type doubling constants q4 and q5 on higher powers of the angular momentum J. This J-dependence was found to be substantially different for the two vibrational modes.The doubling constants given in MHz areq4=23.6722 - (0.6139·10-3) J(J+1) + (0.1417·10-6) [J(J+1)]2-(0199·10-10) [J(J+1)]3,q5=34.6391 - (0.1623·10-3) J(J+1) + (1.00·10-9) [J(J+1)]2.The molecular dipole moment was determined from Stark-effect measurements on the J=0 → 1 transition in the ground state and found to be (3.06 ± 0.15) Debye. The nuclear quadrupole coupling constants for the 14N- and 170-nuclei can be given ase q Q (17O) = — (12.31 ± 0.12) MHz and | e q Q (14N) | ≦ 0.3 MHz.

Synthesis and Microwave Spectroscopic Study of Fluorinated Methyl Isocyanides

1994 ◽  
Vol 49 (6) ◽  
pp. 703-708 ◽  
Author(s):  
M. Krüger ◽  
H. Dreizler ◽  
D. Lentz ◽  
D. Preugschat
Keyword(s):  
Stark Effect ◽  
Continuous Wave ◽  
Spectroscopic Studies ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Flash Vacuum Pyrolysis ◽  
Microwave Spectrometer ◽  
Vacuum Pyrolysis ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

Abstract Difluoromethyl isocyanide has been generated by flash vacuum pyrolysis of pentacarbonyl (di-fluoromethyl isocyanide) chromium at 240 °C. Spectroscopic studies revealed the presence of several major and minor impurities like HCN, HCC -CN and HCC -NC . The pyrolysis of pentacarbonyl (fluoromethyl isocyanide)chromium did not lead to the observation of free fluoromethyl isocyanide. The rotational spectrum of difluoromethyl isocyanide has been recorded with a conventional continuous wave Stark spectrometer and a molecular beam Fourier transform microwave spectrometer resulting in A = 10.110841 (42), B = 4.550914 (19), C = 3.343550 (19) GHz, D′J = 0.41(13), D′JK = 26.72(36), D′J = - 21.3 (18) kHz. The dipole moment components μa = 1.46(1), μc= 1.83 (1) and μtotal 2.34 (1) D were obtained from the second order Stark effect. The 14N nuclear quadrupole hyperfine structure in the rotational spectrum of CHF2-NC has been resolved and the 14N nuclear quadrupole coupling constants xaa = 599.0 (10), xbb = −406.5 (14), xcc= −192.6 (14) kHz have been obtained.

scholarly journals Mikrowellenspektrum, Hinderungspotential der internen Rotation, Quadrupolkopplungskonstanten und Dipolmoment des 2-Methyl-Pyridins

1970 ◽  
Vol 25 (1) ◽  
pp. 25-35 ◽  
Author(s):  
H. Dreizler ◽  
H.D. Rudolph ◽  
H. Mäder
Keyword(s):  
Dipole Moment ◽  
Hyperfine Structure ◽  
Internal Rotation ◽  
Excited States ◽  
Stark Effect ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Microwave Rotational Spectrum ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

Abstract The microwave rotational spectrum of 2-methyl-pyridine (a-picoline) has been investigated in the region from 6 to 30 kmc/s. From the three lowest states of internal rotation m=0, 1, 2 the three-and sixfold components V3 and V6 of the potential barrier hindering the internal rotation have been determined to be V3= (258,4 ± 0,1) cal/mole and V6=(-11,8± 0,1) cal/mole. From the splitting of low-J lines m=0 the nuclear quadrupole coupling constants for the 14N nucleus have been derived as χaa= (-0,33 ± 0,02) mc/s, χbb = (-2,86 ± 0,02) mc/s, χcc = (+3,19 ± 0,02) mc/s. The hyperfine structure of rotational transitions in excited states of internal rotation could also be accounted for with these coupling constants. The dipole moment components derived from Stark-effect measurements in the ground torsional state m = 0 are μa = (0,72 ± 0,01) Debye and μb - (1,71 ± 0,02) Debye.

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