The Rotational Zeeman Effect of Pyrazole and Imidazole

1987 ◽  
Vol 42 (1) ◽  
pp. 49-56 ◽  
Author(s):  
M. Stolze ◽  
D. H. Sutter
Keyword(s):  
Magnetic Susceptibility ◽  
Angular Momentum ◽  
Ring Current ◽  
Zeeman Effect ◽  
Membered Ring ◽  
Ring Molecules ◽  
Isotopic Species ◽  
Out Of Plane ◽  
Additivity Rules ◽  
Single Standard

The rotational Zeeman effect of the most abundant isotopic species of pyrazole and of imidazole has been studied under Δ M= 0 and Δ M = ± 1 selection rules. With field close to 1.9 Tesla, the nuclear Zeeman effect uncouples the rotational angular momentum and the spins of the two nonequivalent 14N quadrupole nuclei. The observed g-tensor elements are gaa = - 0.07498(14), gbb = - 0.12531(13), and gcc = 0.06346(12) for pyrazole and gaa = - 0.09339(16), gbb = - 0.10444(14), and gcc= 0.06051(15) for imidazole. The values for the magnetic susceptibility anisotropies in units of 10-6 erg/(G2 mol) are 2Xaa - Xbb - Xcc = 39.53(24) and 2Xbb - Xcc - Xaa = 51.20(21) for pyrazole and 2xaa - Xbb - Xcc = 45.76(31) and 2Xbb - Xcc - Xaa = 42.19(41) for imidazole. (Given uncertainties are single standard deviations of the fit.) The so-called nonlocal (π-ring current) contributions to the out of plane components of the susceptibility tensor Xccnonlocal, derived as differences between the observed susceptibilities and values calculated from additivity rules for local atom susceptibilities, are compared to those derived earlier for other aromatic five membered ring molecules.

scholarly journals The Rotational Zeeman Effect in Fluorobenzene and the Molecular Quadrupole Moment in Benzene

1982 ◽  
Vol 37 (10) ◽  
pp. 1165-1175 ◽  
Author(s):  
W. H. Stolze ◽  
M. Stolze ◽  
D. Hübner ◽  
D. H. Sutter
Keyword(s):  
Magnetic Susceptibility ◽  
Carbon Tetrachloride ◽  
Quadrupole Moment ◽  
Ring Current ◽  
Zeeman Effect ◽  
Electric Quadrupole ◽  
Quadrupole Moments ◽  
Electric Quadrupole Moment ◽  
Microwave Spectrometer ◽  
Out Of Plane

The rotational Zeeman effect in fluorobenzene is reinvestigated with a resolution improved by a factor of almost five to give more accurate g-tensor elements, magnetic susceptibility anisotropics and molecular electric quadrupole moments. The results fit into the pictures of a linear dependence of the out of plane molecular electric quadrupole moment, Qcc, on the number of fluorine substituents and of a linear correlation between the nonlocal (ring current) susceptibility, Χccnonlocal, and the CNDO/2-π-electron density alternation. They lead to a gasphase molecular electric quadrupole moment in benzene, Qcc,benzene = - (28.4 ± 4.7) · 10-40 Cm2 which is slightly less negative than the value deduced from electric field-gradient birefringence experiments on dilute benzene solutions with carbon tetrachloride as solvent. A detailed description of the high resolution microwave spectrometer is given in the appendix.

Molecular g-Values, Magnetic Susceptibility Anisotropics and Molecular Electric Quadrupole Moment of Methylenecyclobutenone

1974 ◽  
Vol 29 (12) ◽  
pp. 1820-1826 ◽  
Author(s):  
W. Czieslik ◽  
D. H. Sutter
Keyword(s):  
Experimental Data ◽  
Magnetic Susceptibility ◽  
Quadrupole Moment ◽  
Zeeman Effect ◽  
Electric Quadrupole ◽  
Quadrupole Moments ◽  
Electric Quadrupole Moment ◽  
Ring Molecules ◽  
Indo Calculations ◽  
Additivity Rules

The rotational Zeeman-effect of methylenecyclobutenone has been investigated giving the molecular (g-values: gaa = -0.0925 ± 0.0003, gbb = -0.0729 ±0.0003, gcc = -0.0086 ± 0.0003 and the magnetic susceptibility anisotropies: 2χaa-χbb-χcc= (23.0 ± 0.5) · 10-6 erg/G2 mole and 2χbb-χcc-χaa= (25.5 ± 0.5) · 10-6 erg/G2 mole. These values correspond to the following molecular electric quadrupole moments given in units of 10-28 esu cm2: Qaa = 1.0±0.6, Qbb= 2.8±0.6 and Qcc = 3.8± 1.0. The experimental data of methylenecyclobutenone and similar strained ring molecules are compared with the results of INDO-calculations and values obtained from additivity rules for bond contributions.

Molecular g-Values, Magnetic Susceptibility Anisotropics, Second Moments of the Charge Distribution, and Molecular Electric Quadrupole Moments in trans- and cis-Thioformic Acid

1978 ◽  
Vol 33 (1) ◽  
pp. 29-37 ◽  
Author(s):  
G. K. Pandey ◽  
D. H. Sutter
Keyword(s):  
Magnetic Susceptibility ◽  
Charge Distribution ◽  
Zeeman Effect ◽  
Electric Quadrupole ◽  
Covalent Bonding ◽  
Microwave Spectrum ◽  
Quadrupole Moments ◽  
Second Moments ◽  
In Trans ◽  
Single Standard

The rotational Zeeman effect in the microwave spectrum of trans- and cis-Thioformic Acid has been investigated at field strengths upto 25.6 kG. Measurements were done for both ⊿M = 0 and ⊿M = ± 1 selection rules for the trans species and for ⊿M = ±1 for the cis species. From the observed splittings the following parameters were obtained for the diagonal elements of the molecular g tensor and the susceptibility anisotropics.(all experimental uncertinties are single standard deviations).The molecular electric quadrupole moments derived from the Zeeman data indicate that there is no significant covalent bonding in the O…H region of the trans species.

Der Zeemann-Effekt im Rotationsspektrum von 2-Fluoropyridin

1971 ◽  
Vol 26 (10) ◽  
pp. 1644-1657 ◽  
Author(s):  
D. Sutter
Keyword(s):  
Magnetic Susceptibility ◽  
Liquid Phase ◽  
Gas Phase ◽  
Crystalline Phase ◽  
Zeeman Effect ◽  
Short Description ◽  
Rotational Spectrum ◽  
Magnetic Susceptibility Anisotropy ◽  
Out Of Plane ◽  
Phase Out

Abstract The molecular Zeeman effect has been observed in the rotational spectrum of 2-fluoropyridine at magnetic fields close to 25000 G. The measured molecular g-values are gaa = -0.0880 ± 0.0007, gbb = - 0.0405 ±0.0006, gcc = + 0.0233 ±0.0006, and the two linearily independant components of the magnetic susceptibility anisotropy are 2 · χaa - χbb - χcc = 50.5 ± 1.6 and 2 · χbb - χcc - χaa - 53.8 ± 1.1 in units of 10-6 erg/G2 mol). The a-axis is close to the C-F-bond and the c-axis is perpendicular to the plane of the ring. A comparison of the gas-phase out-of-plane minus the average in-plane values for the susceptibilities of 2-fluoropyridine, pyridine, and fluorobenzene with the corresponding value for benzene in crystalline phase leads to the conclusion that the susceptibilities may change in the order of 10% when going from solid or liquid phase to the gasphase. A short description of the microwave-Zeeman spectrograph built at Kiel University is given. In the theoretical section expressions for the g-values and susceptibilities are derived which are more complete then those used up to now.

The Molecular Zeeman Effect in 2-Methylfuran

1973 ◽  
Vol 28 (12) ◽  
pp. 1906-1910 ◽  
Author(s):  
W. Czieslik ◽  
U. Andresen ◽  
H. Dreizler
Keyword(s):  
Magnetic Susceptibility ◽  
Standard Deviation ◽  
Zeeman Effect ◽  
Methyl Group ◽  
Out Of Plane

The rotational Zeeman effect in 2-methylfuran has been measured and the results are compared with those of furan. The Zeeman parameters for the torsional A-species are gaa = -0.0704 ± 0.0005, gbb = -0.0335 ± 0.0004, gcc = +0.0253 ± 0.0005, 2 χaa - χbb - χcc = (23.6 ±0.9) · 10-6 erg/(G2 mole), 2 χbb - χaa - χcc = (44.2 ± 0.7) · 10-6 erg/(G2mole). The corresponding values of the torsional E-species agree with those of the A-species within twice the standard deviation.The out-of-plane minus the average in-plane components of the magnetic susceptibility, ⊿χ = χcc - 1/2 (χaa + χbb), for 2-methylfuran and furan are compared. The substitution of a methyl group for a proton in the 2-position of furan changes ⊿χ by + (4.8 ± 1.0) · 10-6 erg/(G2mole).

Vibrational Dependence in the Molecular G- and Susceptibility- Tensors of Sulfur Dioxide

1984 ◽  
Vol 39 (1) ◽  
pp. 63-65
Author(s):  
D. Hübner ◽  
D. H. Sutter
Keyword(s):  
Magnetic Susceptibility ◽  
Dipole Moment ◽  
Excited State ◽  
High Resolution ◽  
Small Amplitude ◽  
High Field ◽  
Zeeman Effect ◽  
Bending Vibration ◽  
Isotopic Species ◽  
First Excited State

The high field rotational Zeeman effect of SO2 molecules in the first excited state of the bending vibration has been studied under high resolution. Within the experimental uncertainties no υ-dependence is observed for the magnetic susceptibility anisotropies, and the observed υ-dependence in the g-tensor elements appears to be essentially caused by the υ-dependence of the rotational constants. If this finding may be generalized to all small amplitude vibrations, prospects for sign of the electric dipole moment determinations from rotational Zeeman effect studies of different isotopic species are brighter than expected hitherto.

scholarly journals Quantum Control of Coherent π-Electron Dynamics in Aromatic Ring Molecules

2021 ◽  
Vol 9 ◽  
Author(s):  
Hirobumi Mineo ◽  
Ngoc-Loan Phan ◽  
Yuichi Fujimura
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Aromatic Ring ◽  
Excited States ◽  
Quantum Control ◽  
Ring Current ◽  
Theoretical Description ◽  
Electron Dynamics ◽  
Ring Molecules ◽  
Electron Ring

Herein we review a theoretical study of unidirectional π-electron rotation in aromatic ring molecules, which originates from two quasi-degenerate electronic excited states created coherently by a linearly polarized ultraviolet/visible laser with a properly designed photon polarization direction. Analytical expressions for coherent π-electron angular momentum, ring current and ring current-induced magnetic field are derived in the quantum chemical molecular orbital (MO) theory. The time evolution of the angular momentum and the ring current are expressed using the density matrix method under Markov approximation or by solving the time-dependent Schrödinger equation. In this review we present the results of the following quantum control scenarios after a fundamental theoretical description of coherent angular momentum, ring current and magnetic field: first, two-dimensional coherent π-electron dynamics in a non-planar (P)-2,2’-biphenol molecule; second, localization of the coherent π-electron ring current to a designated benzene ring in polycyclic aromatic hydrocarbons; third, unidirectional π-electron rotations in low-symmetry aromatic ring molecules based on the dynamic Stark shift of two relevant excited states that form a degenerate state using the non-resonant ultraviolet lasers. The magnetic fields induced by the coherent π-electron ring currents are also estimated, and the position dependence of the magnetic fluxes is demonstrated.

Nonlocal Susceptibilities and Molecular Electric Quadrupole Moments of 3-Fluoropyridine and 2,6-Difluoropyridine, a Rotational Zeeman Effect Study

1981 ◽  
Vol 36 (4) ◽  
pp. 332-346 ◽  
Author(s):  
D. Hübner ◽  
M. Stolze ◽  
D. H. Sutter
Keyword(s):  
Magnetic Susceptibility ◽  
Zeeman Effect ◽  
Electric Quadrupole ◽  
Effect Study ◽  
Quadrupole Moments ◽  
Molecular Plane ◽  
Magnetic Susceptibilities ◽  
Straight Line ◽  
Out Of Plane ◽  
Experimental Values

The rotational Zeeman effect spectra of 3-Fluoropyridine and 2,6-Difluoropyridine have been measured. The molecular g-values are gaa = - 0.0917(5), gbb = - 0.0476(5), gcc = +0.0194(5) for 3-Fluoropyridine and gaa= -0.0573(6), gbb =0.0311(6), gcc =0.0102(6) for 2,6-Difluoro- pyridine. The values for the magnetic susceptibility anisotropics in units of 10-6 erg/(G2 mol) are 2Xaa+Xbb + Xcc = 53.3(8), 2Xbb-Xcc-Xaa = 60.5(7) for 3-Fluoropyridine and 2Xaa-Xbb -Xcc = 48.4(11), 2Xbb-Xcc-Xaa=51.7(11) for 2,6-Difluoropyridine. Subtraction of the local atom contributions to the magnetic susceptibilities indicates that Fluorine quenching of the nonlocal out of plane contribution depends on the position of the substituent. Further, the data suggest a linear correlation between X⟂nonlocal and the “CNDO/2-π-density alternation”, which is used to predict susceptibility anisotropics of Fluorobenzenes and Fluoropyridines not yet measured.The molecular quadrupole moments are calculated from the Zeeman data and compared with the experimental values obtained for various fluorosubstituted Pyridines and Benzenes. If the quadrupole moments perpendicular to the molecular plane are referred to the centers of the six membered rings and are plotted against the number of Fluoroine substituents, nF, the plots closely follow a straight line with identical slopes for the Pyridine- and Benzenefamilies, but with different intercepts at nF = 0. From the “nF = 0 intercept” for the Fluorobenzenes we conclude that the Benzene quadrupole moment proposed earlier by Shoemaker and Flygare should probably be revised

On the Validity of Additivity Rules for the Molecular Magnetizability Tensor and the Molecular g-Tensor in van der Waals Complexes. A Rotational Zeeman Effect Study o f 1,1-Dideutero-Cyclopropane

1994 ◽  
Vol 49 (4-5) ◽  
pp. 585-588
Author(s):  
O. Böttcher ◽  
V. Meyer ◽  
D. H. Sutter
Keyword(s):  
Magnetic Susceptibility ◽  
Zeeman Effect ◽  
Van Der Waals ◽  
Degree Of Approximation ◽  
Effect Study ◽  
Van Der Waals Complexes ◽  
Magnetic Susceptibility Anisotropy ◽  
Extra Information ◽  
Additivity Rules ◽  
High Degree

AbstractThe molecular g-tensor and the magnetic susceptibility anisotropy of cyclopropane were deter­ mined by a microwave Fourier transform study of the rotational Zeeman effect of its 1,1-dideuterated isotopomer. The results g⊥ = 0.02675(23), g∥ = 0.06998(23), and ξ⊥ - ξ ∥ = 8.80(31) · 10-6 erg G-2 mol-2 are in agreement with values determinea indirectly from van der Waals complexes. This finding provides experimental evidence that in van der Waals molecules additivity rules might hold to a high degree of approximation for both types of tensors. Rotational Zeeman effect studies of van der Waals complexes may thus provide valuable extra information on their structures.

First-principles study of carbon nanothreads derived from five-membered heterocyclic rings: thiophene, furan and pyrrole

2020 ◽  
Author(s):  
Pedro Guerra Demingos ◽  
Naira Maria Balzaretti ◽  
André Muniz
Keyword(s):  
First Principles ◽  
Membered Ring ◽  
One Dimensional ◽  
Aromatic Molecules ◽  
First Principles Study ◽  
Ring Molecules

Carbon nanothreads are one-dimensional materials obtained by controlled compression of aromatic molecules. Benzene and other six-membered ring molecules are normally used as precursors, but recent experiments have shown that carbon...

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