Magnetic hyperfine spectrum

Fig. 7.45 Outer two components of the magnetic hyperfine spectrum of a W/W source versus a Ta absorber, measured at zero velocity as a function of a longitudinal magnetic field ( Zeeman drive experiment) (from [185])...

The superparamagnetic properties of -Fe203 have also been studied via the Mossbauer effect. Nakamura et al, (32) have investigated the temperature dependence of the internal field in -Fe203 particles of approximately 50 A. diameter. At 120 °K. they obtain a spectrum which is almost identical to the bulk material, except that no Morin transition has occurred and the spins still lie in the basal plane. At room temperature the magnetic hyperfine spectrum collapses (even though the bulk... 

Figure 3. Magnetic hyperfine spectrum of Te as impurity in metallic Fe...

Other physical properties also show that the iron cores of native ferritins and bacterioferritins are different. Mossbauer spectra of ferritins measured as a function of temperature (Fig. 1) show quadrupole split doublets, with an isomer shift typical of Fe +, gradually being replaced as the temperature is lowered (between about 50 and 15 K) by a magnetic hyperfine spectrum (30, 31). The transition temperature, Tb, is lower than the ordering temperature, Tord (240 K) observed for bulk ferrihydrite (32), because of fluctuations in the direction of mag-... 

For the analysis of the magnetic hyperfine spectrum of HbCO (Fig. 7b) the approximation AEq > AEyi ( 3/2) is no longer valid. In this more general case the Fe57 nuclear eigenstates were derived with the aid of the hamiltonian. 

The appropriate theory for a magnetic hyperfine spectrum was given... 

Only brief details are available for anhydrous iron(III) sulphate it gives a paramagnetic spectrum at room temperature [111] with a chemical isomer shift of 0-39 mm s and a quadrupole splitting of 0-60 mm s" [9]. A sharp magnetic hyperfine spectrum is seen at 1-8 K with a field of 550 kG [98]. 

The magnetic hyperfine spectrum of Sm in samarium iron garnet is shown in Fig. 17.5 and comprises five lines as expected for a O" " ->2 ... 

The orthochromite, DyCrOa, is paramagnetic above the Neel temperature of 2-16 K, but at 4-2 K a well-resolved magnetic hyperfine spectrum is seen because of a long paramagnetic relaxation time [107]. The parameters (Table... 

Major, F.G. Werth, G. Magnetic hyperfine spectrum of isolated (mercury-199) + ions. 

In practical applications it may happen that the magnetic and quadrupole hyperfine interactions occur simultaneously and the spectra are superimposed on one another. Such a case for iron is presented in Fig. 11 where the effect of first-order quadrupole perturbation on a magnetic hyperfine spectrum is shown. It is evident that the detailed interpretation of this Mossbauer spectrum is quite complex. 

Fig. 9. Magnetic hyperfine spectrum of Np in ferromagnetic NpAl2 at 4.2 K. The source is Am metal which emits an unsplit line. The theoretical spectrum (broken line) is calculated according to the bar diagram of fig. 8. From the line positions one obtains = 330 T.

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