Hyperfine Interaction Constants

The value of the magnetic hyperfine interaction constant C = 22.00 kHz is supposed to be reliably measured in the molecular beam method [71]. Experimental data for 15N2 are shown in Fig. 1.24, which depicts the density-dependence of T2 = (27tAv1/2)-1 at several temperatures. The fact that the dependences T2(p) are linear until 200 amagat proves that binary estimation of the rotational relaxation rate is valid within these limits and that Eq. (1.124) may be used to estimate cross-section oj from... 

The shifts in the 113Cd spectra due to the electron hyperfine interaction from an Mn++ ion two bonds distant could then be used to obtain a transferred hyperfine interaction constant A that could be compared to the value obtained from ESR measurements. For 125Te, the nearest neighbor Mn++ apparently broadened the NMR signal beyond detectability the transferred hyperfine interaction constant A for Mn++ ions in the second shell was calculated from the 125Te shifts. 

The 113Cd Ti values estimated for the various peaks varied from 10 to 50 ms and obeyed the qualitative dependence upon 1/R6 (R = Mn-Cd distance) of the dipolar relaxation mechanism expected to be operative. The broad line widths were also shown to have significant contributions from the T2 relaxation induced by Mn++, with both dipolar and contact terms contributing. The 113Cd shifts of the peaks assigned to different shells were measured as a function of temperature, and observed to follow a linear 1/T dependence characteristic of the Curie-Weiss law, with slopes proportional to the transferred hyperfine interaction constant A. 

In a study of the isotropic proton hyperfine interaction constants for various Fe(R2Dtc)3 complexes and their redox behavior, a simple relationship... 

The structure of radicals II is confirmed by quantum-chemical calculations of hyperfine interaction constants [9],... 

From the variations of shifts with solute concentrations the structures of the second coordination spheres are postulated. In the case of Co(C104)2 in the presence of aqueous acetone, mono-, bis-, and tris-acetone complexes are suggested. (272) In contrast Co(N03)2 solutions behave quite differently. Knowledge of the temperature dependences of the shifts has enabled the hyperfine interaction constants to be calculated in some cases. 

The formation of platinum(III) [Pt(diAMsar)] + sarcophaginate by the y-radiolysis of [Pt(diAMsar)]X4 samples (where X = CF or CF3SO3I was detected by EPR spectroscopy [156], The strong split signals in the EPR spectra were observed at 4 and 77K and did not disappear even after storage of the samples at room temperature for several days. Since i Pt isotope with nuclear spin 1 - 1/2 is a dominant, the EPR spectrum must contain a triplet with the relative peak intensities equal to 1 4 1. Nearly the same spectrum (g = 2.01, the hyperfine interaction constant A 50G) was observed for [Pt(diAMsar)](CF3SO),3 sarcophaginate. For a chloride complex, the spectrum (g = 2.01, A 60G) is more diffuse, which may be due to the... 

Here g and gjL are the electronic g factors for the magnetic field, respectively parallel and perpendicular to the symmetry axis, A is now the isotropic hyperfine interaction constant, and B is the anisotropic hyperfine interaction constant. The dependence on magnetic field orientation is given by the function (3 cos —1), where Oh is the angle between the magnetic field and the symmetry axis. 

Systematic and extensive measurements of nuclear spins, hyperfine interaction constants such as the dipole, the quadrupole have for a long time been... 

Several authors have measured the copper and cobalt hyperfine interaction constants, A and B (Table VI), arising from coupling between the electronic spin and the nuclear spin of the central metal ion. Four lines are seen in the case of copper phthalocyanine due to interaction between the electron and the nuclear spin of Cu83 (I = ) single crystals of cobalt phthalocyanine diluted in zinc phthalocyanine gave eight components due to interaction with the nucleus of Co69 (I = ) (167). 

A,B are metal, and C,D are nitrogen hyperfine interaction constants in wave numbers. Q is a quadrupole interaction constant in oo... 

Making use of electron-spin resonance in the radical-ion salts, in particular the diffusion constant D and the hyperfine interaction constant A of the electron spins can be measured. One thus obtains independent information on the dynamics and the spatial distribution of the conduction electrons within the stacks. 

Hyperfine interaction constant for nuclear spin-electron spin interaction... 

Hyperfine Interaction Constants. In the doublet states X 11 and A A, where the unpaired electron occupies the 2n or the 5o MO, respectively, hyperfine Interaction occurs between the electron spin (S=1/2) and the nuclear spin of P (1=1/2) or (1=1/2). This results in a splitting of the rotational levels into four sublevels. Hf splitting of the rotational lines have been observed in the v=1<-2 band of the A A -X rir system applying high-resolutlon laser photofragment spectroscopy [12, 13]. The following Frosch-Foley hf interaction constants a, bp (=b + c/3), c, d (see [36, pp. 34/8]) for the ip and nuclei have been derived (constants In MHz three standard deviation in parentheses) [13] ... 

The final result for the magnetic dipole hyperfine interaction constant as obtained from this experiment is... 

The ground state hyperfine structure splitting of Be was measured by optical pumping and rf transitions between suitable (M/, Mj) substates in magnetic fields of roughly 0.7-0.8T. The respective transitions were induced with two coherent rf pulses of 0.S sec duration separated by 19 sec. This Ramsey interference method provides signal linewidths dominated by the pulse separation time. The obtained magnetic hyperfine interaction constant of... 

This magnetic interaction, between the muon and the electron for the spherically symmetrical s state, sums to zero except where the electronic wavefunction overlaps the nucleus, hence the name contact interaction . Therefore the resulting hyperfine interaction constant. A, is a measure of the electron density at the nucleus. 

McConnell (79, 80) supposed that the hyperfine interaction constant would be proportional to the fraction of an unpaired electron that was... 

Finally it must be emphasized that the empirical relation between proton chemical shifts and charge densities is not so firmly established as the corresponding relation for the ESR hyperfine interaction constant 15). Many theoretical and experimental points remain to be clarified. 

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