Nuclear gamma resonance

Litvinov V.S., Carakishev S.D., Ovchinnikov V.D. (1982), Nuclear gamma-resonance spectroscopy of alloys, Moscow, Metallurgy, Russia, 144. 

Consequently, Au(in) and Au(I) compounds have been the subject of extensive investigations by nuclear gamma resonance spectroscopy. The results revealed a dependence of the isomer shift on the oxidation state similar to that found in compounds of the 3d, 4d, and 5d transition elements, e. g., "Fe, Ru, Ir, and Os. On the other hand, appreciable variation of the isomer shift within the same oxidation state was observed for Au(I) and Au(ni) compounds, much as in the cases of Ru(n) and Ru(m), Ir(ni), and Fe(H) low-spin complexes, indicating a marked dependence of the isomer shift upon the nature of the ligands. 

Magnetic and nuclear gamma resonance (NGR) parameters of EuO Fe composites are studied. Their properties really meet the requirements imposed on the use of them as spin injectors in semiconductor spin-electronic structures capable of operating under normal conditions at room temperatures. 

Fig. 1.3 The resonance overlap for free-atom nuclear gamma resonance is small and is shown shaded in black.

Ale] Electron diffraction, nuclear gamma resonance Order-disorder kinetics in Co-Fe equiatomic alloys + V... 

Ser] Nuclear magnetic resonance, nuclear gamma resonance, magnetometry, magnetic annealing 5-20 mass% Co, 25-30 mass% Cr, Fe = bal. 620-660 spinodal decomposition in bcc phase... 

Kaipov DK (1976) Nuclear gamma resonance and its related processes. Naul, Alma Ata Kajcsos Z, Alflen M, Spiering H, Gutlich P, Albrecht R, Schulze R, Kurz R (1986) Hyperfine Interact 29 1551 Kajcsos Z, Sauer Ch, Holz rth A, Kurz R, Zinn W, Ligtenberg MAC, Van Aller G (1988) Nucl Instr Meth Phys Res B 34 384... 

Table 9. Data obtained by nuclear gamma resonance (compositions according to Table 11).

The methods of nuclear magnetic resonance (NMR) and of Mossbauer effect or nuclear gamma resonance (NGR) spectroscopy furnish a broad basis for the study of the structural, electronic, and magnetic properties of rare-earth metals, alloys, and compounds. Taken together, there is hardly a rare-earth or non rare-earth nucleus whose hyperfine interactions cannot be measured. In many cases, results can be cross-checked with measurements on several isotopes of the same element. 

In nuclear gamma resonance (Mossbauer effect) experiments, the nuclear hyperfine interactions are measured via their influence on the energy of the gamma ray emitted (or absorbed) when the nucleus undergoes a transition between an excited state and its ground state (or between two excited states). Since the nuclear hyperfine energies are small ( 10" -10 eV) compared with... 

Nuclear moment properties of the ground and excited states of selected rare-earth nuclei frequently utilized in nuclear gamma resonance (Mossbauer effect) measurements, adapted from Stevens and Dunlap (1976). Nuclear moment values are given in units of the nuclear magneton... 

Relaxation effects in Mossbauer spectroscopy are of a different nature from those in NMR. The term relaxation effects or relaxation spectra in nuclear gamma resonance spectroscopy refers to averaging effects that occur in the hyperfine spectrum when the hyperfine interactions fluctuate at a rate more rapid than the nuclear frequency characteristic of the hyperfine interaction itself. This situation is a consequence of the rapid relaxation of the host ion among its energy levels, and the relaxation time for such effects is characteristic of the ion and not of the nuclear spins. The relaxation processes involved also affect electron spin resonance spectra, and their discussion is best considered in that context (see sections 3.3. and 3.4.). In the following subsections the principal interactions which contribute to the nuclear spin relaxation times in NMR experiments are briefly considered, and the connections between these and the parameters characterizing the steady-state spectrum are outlined. 

Resume of nuclear gamma resonance studies and results in the magnetically ordered state of lanthanide metals and alloys. The magnetie hyperfine parameter a (or effective field, Hch) and quadrupole coupling parameter P are obtained by fitting eq. (18.70) to the experimental data. 

Resumd of nuclear gamma resonance measurements on lanthanide nuclei in the paramagnetic state of lanthanide metals and alloys. 

Resume of representative nuclear gamma resonance studies of non-rare earth nuclei in the magnetically ordered state of intermetallic compounds. Unless otherwise noted, the interaction parameters measured were the effective hyperhne field, quadrupole coupling, and isomer shift. 

Resume of representative nuclear gamma resonance studies of rare earth nuclei in the paramagnetic state of intermetallic compounds... 

Relaxation effect in nuclear gamma resonance spectra... 

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