Mossbauer 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...

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])...

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. 

Fig. 1.6 Shift and splitting of nuclear levels of nucleus by the hyperfine interactions and expected Mossbauer spectra, a Center shift of the observed absorption line. In this case the observed shift is the sum of isomer shift and second order Doppler shift, b Electric quadrupole splitting AEq and c magnetic h5 perfine splitting that is a nuclear Zeeman splitting. is the magnitude of the hyperfine magnetic field at nucleus...

In contrast to the neutron diffraction which reflects the spatial correlation of spins, Mossbauer spectroscopy reveals information on the time correlation of one spin. If the system is not in thermal equilibrium, these two correlations are not identical. In addition, information can be drawn from the Mossbauer spectra on the electronic state including the charged state of the Fe atoms from the isomer shift, the electric quadrupole splitting and Zeeman splitting due to the internal field. When the specimen is a single crystal, the spin direction can also be determined from intensities of each component of the sextet. 

Figure 4.54 The effect of an electric field gradient (EFG) creating asymmetry in the electron distribution round a gold nucleus, leading to a quadrupole splitting in the Mossbauer spectrum. (Reproduced with permission from Gold Bull., 1982,15, 53, published by World Gold Council.)...

Fig. 4.6 Quadrupole splitting of the excited state of Fe with I = 3/2 and the resulting Mossbauer spectrum. Quadrupole interaction splits the spin quartet into two degenerate sublevels 7, OT/) with energy separation A q = 2 q. The ground state with I = 1/2 remains unsplit. The nuclear states are additionally shifted by electric monopole interaction giving rise to the isomer shift 8...

We have learned from the preceding chapters that the chemical and physical state of a Mossbauer atom in any kind of solid material can be characterized by way of the hyperfine interactions which manifest themselves in the Mossbauer spectrum by the isomer shift and, where relevant, electric quadrupole and/or magnetic dipole splitting of the resonance lines. On the basis of all the parameters obtainable from a Mossbauer spectrum, it is, in most cases, possible to identify unambiguously one or more chemical species of a given Mossbauer atom occurring in the same material. This - usually called phase analysis by Mossbauer spectroscopy - is nondestructive and widely used in various kinds of physicochemical smdies, for example, the studies of... 

Mossbauer isomer shift and quadrupole splitting are commonly used to obtain information about the bonding environment around source nuclides. The isomer shift arises from the electric monopole interaction of the nucleus with the electrons and depends on the... 

Fig. 7.4 Top Nuclear energy levels of Fe as shifted by electrical monopole (left), or as split by electrical quadrupole (center) or by magnetic dipole interaction (right), schematized for hematite at room temperature (5 > 0 vs. a-Fe, EQ < 0, Bhf 0). Bottom Schematic Mossbauer spectra corresponding to the energy levels schematized on top (J. FriedI, unpubl.).

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