Hyperfine splitting measurement

Cahbration spectra must be measured at defined temperamres (ambient temperature for a-iron) because of the influence of second-order Doppler shift (see Sect. 4.2.1) for the standard absorber. After folding, the experimental spectrum should be simulated with Lorentzian lines to obtain the exact line positions in units of channel numbers which for calibration can be related to the hteramre values of the hyperfine splitting. As shown in Fig. 3.4, the velocity increment per channel, Ostep, is then obtained from the equation Ustep = D,(mm s )/D,(channel numbers). Different... 

McCammon et al. have studied fine nickel particles using Ni Mossbauer spectroscopy [22]. The measured average hyperfine field of 10 nm particles at 4.2 K was 7.7 T for nickel foil, it was found to be 7.5 T. Application of an external magnetic field of 6 T caused a reduction of the hyperfine splitting to 1.5 T as a consequence of the negative hyperfine field at Ni nuclei. 

Heuberger et al. [272] and an Israeli group [271] have, independently from each other and at nearly the same period, measured the hyperfine splitting and the isomer... 

EPR. The EPR for 48 has been reported. The frozen solution spectrum measured in concentrated sulfuric acid is typical of a monomeric square-planar Cu(II) complex with axial g tensor and 63 65Cu hyperfine splitting (hfs) tensor. The measured parameters are compared to Cu(TPP) and Cu pc in Table XI. 

In the ESR spectra of adsorbed oxovanadium(IV) ions on minerals, Information on the nature of the adsorbed species is obtained from the g-values and V hyperfine coupling constants, but ligand hyperfine structure is seldom, if ever, observed. With ENDOR much smaller hyperfine splittings can be observed than with ESR and it is possible to measure hyperfine coupling from nuclear spins in... 

Spin-density distributions are inherent features of free radicals. Esr experiments take place when the radical is in its electronic ground state and the measurement of the spin distribution constitutes only a minute perturbation of the system. This feature and the fact that esr hyperfine splitting can be measured with high precision makes the esr method ideally suited for the study of substituent effects. Therefore, if spin delocalization is accepted as a measure of stabilization, the data in Table 6 provide quantitative information. However, these are percentage values and not energies of stabiliza-... 

The electron spin resonance (ESR) spectra of the radical anion of 2,2 -bipyridine, sometimes in the form of its alkali metal com-plgx, 71.175,177.299-304 radical anion of 3,3 -bipyridine, ° and the radical anion of 4,4 -bipyridine, ° ° usually obtained by reduction of the bipyridines with an alkali metal, have been measured, and hyperfine splitting constants were assigned. Related biradical species have also been investigated. The ESR spectrum of the 4,4 -bipyridinium radical cation, of which... 

The hyperfine splitting in the ground state of hydrogen is one of the most precisely measured quantities in modern physics [1, 2] (see for more details Subsect. 12.2.1 below), and to describe it theoretically we need to consider additional contributions to HFS connected with the bound state nature of the proton. 

Hyperfine splitting in the ground state of hydrogen was measured precisely more than thirty years ago [65, 66]... 

The hyperfine splitting in the ground state of deuterium was measured with very high accuracy a long time ago [70, 71[... 

The reported ESR spectra of polyisobutylene, irradiated with high energy radiation and measured at low temperatures (31, 35, 47, 48, 49, 52) are similar in form, showing a broad doublet with a hyperfine splitting constant of 20 gauss. These spectra have been interpreted as caused by radicals (XIII) formed by hydrogen abstraction from the main chain methylene groups ... 

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