Electric quadrupole splitting

Fig. 4.13 Combined magnetic hyperfine interaction for Fe with strong electric quadrupole interaction. Top left, electric quadrupole splitting of the ground (g) and excited state (e). Top right first-order perturbation by magnetic dipole interaction arising from a weak field along the main component > 0 of the EFG fq = 0). Bottom the resultant Mossbauer spectrum is shown for a single-crystal type measurement with B fixed perpendicular to the y-rays and B oriented along...

If the electric quadrupole splitting of the 7 = 3/2 nuclear state of Fe is larger than the magnetic perturbation, as shown in Fig. 4.13, the nij = l/2) and 3/2) states can be treated as independent doublets and their Zeeman splitting can be described independently by effective nuclear g factors and two effective spins 7 = 1/2, one for each doublet [67]. The approach corresponds exactly to the spin-Hamiltonian concept for electronic spins (see Sect. 4.7.1). The nuclear spin Hamiltonian for each of the two Kramers doublets of the Fe nucleus is ... 

The nuclear Zeeman effect is not a very strong interaction as compared to electric quadrupole splitting because of the relatively weak nuclear magneton. A field of B... 

Fig. 7.41 Electric quadrupole split Ta (6.2 keV) Mossbauer spectra for sources of diffused into hexagonal transition metals (Re, single crystal Os, polycrystallme Ru, single crystal). The isomer shifts relative to a tantalum metal absorber are indicated by the arrows (from [186, 189])...

Both Fe(ll)(TPP) and Fe(II)(OEP) have positive electric quadrupole splitting without significant temperature dependence which, however, cannot be satisfactorily explained within the crystal field model [117]. Spin-restricted and spin-unrestricted Xoi multiple scattering calculations revealed large asymmetry in the population of the valence orbitals and appreciable 4p contributions to the EFG [153] which then was further specified by ab initio and DFT calculations [154,155]. 

Electric quadrupole splitting AEq is only observed with nuclei exhibiting non-spherical charge distribution (nuclear spin and for compounds with aniso-... 

E2) gamma transition of monoisotopic Au is well suited for chemical applications of Mossbauer spectroscopy , since the observed ranges of isomer shifts and electric quadrupole splittings amount to several experimental linewidths. 

The results for the isomer shift S of the quinque-valent compounds, listed in Column of Table I, are almost identical with each other, supporting the existence of similar AuF anions in all of the studied quinquevalent gold compounds. This has also been concluded from the close similarity of the Raman spectra obtained for these complexes. The results for isomer shift and electric quadrupole splitting found for AuF, agree well with those given in Ref. 4. 

Fig. 2. Resonance absorption between the nuclear ground state and the first excited state in 57Fe. The upper diagram shows the effect of an electric quadrupole splitting while the lower diagram shows the magnetic splitting of the nuclear levels...

Equation 3 neglects effects of anisotropic motion on both longitudinal and transverse relaxation rates 2). Recent experiments using deuterium NMR on samples similar to those studied here show significant nuclear electric quadrupole splittings that imply an anisotropic component in the water molecule motion ( ). Such motional anisotropy will depress and elevate T]. 

Electric quadrupole splitting, QS Magnetic hyperfine splitting, MHS... 

Electric quadrupole splitting QS epzz, electric field gradient at the nucleus... 

Two typical results from many measurements are illustrated in Figs 3.46 and 3.47. Figure 3.46 shows correlations between the isomer shift and the electric quadrupole splitting values for Fe in various divalent and trivalent high-spin compounds and for a few low-spin compounds and pressure shifts. In Fig. 3.47, simitar data are plotted for Au in the Au(i) and Au(iii) configurations. Both these figures illustrate, quite clearly, that characteristic... 

Fig. 3.46 Changes in the isomer shift and electric quadrupole splitting under pressure, where the regions of high-spin Fe and Fe and of low-spin Fe(ii) and Fe(iii) can clearly be distinguished.

Fig. 3.47 Changes in the isomer shift and the electric quadrupole splitting for various gold compounds under pressure. o = Au(l) = Au(lll) (ambient pressure.) = Au(l) = Au(lll) arrows indicate the effect of high pressure. (Reprinted with permission of the publisher.)...

Fig. 17.18 The reduced values of the magnetic dipole, H T), and electric quadrupole splittings, q T), in Dy metal as a function of temperature, T. The solid lines represent predictions based on a flee-ion model, and Tn is the Neel temperature. [Ref. 96, Fig. 3]...

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