Hyperfine very large

Absorptions other than those assigned to the Fe(III) complex are observed. The absorption atg = 1.99 is assigned to the superoxide ion ( 02 ) (23). There is a very broad band centered atg = 2.04 that has hyperfine splittings. Each hyperfine constant is very large ( 20 G) compared with those for the pyrryl 7r-radicals (24) a large hyperfine constant is characteristic of the a-radical. Therefore, this radical can be identified as the skatole a-radical (III). 

The 139La nucleus has a spin of 7/2 the Fermi contact hyperfine interaction is large in the B state and very large in the X state. Consequently the B -> A fluorescence spectrum exhibits a distinctive hyperfine structure, an example of which... 

The only rigorous quantum number is F, although N may also be taken as good since the separation of different N levels is very large compared with the dipolar hyperfine interaction. Hence the problem of deriving expressions for the energies of the hyperfine levels in 17,1 is tackled by setting up the five matrices for F = N + 2... 

The hyperfine coupling for the methyl protons (.<4i,o = 5T G) is markedly less than the proton hyperfine coupling observed for the formyl radical ( iBo= 130 G) and could arise from the normal hyperfine interactions observed in alkyl radicals in which the unpaired electron is located in a carbon 2p-orbital. However, the very large splitting in the formyl radical is attributed to a contribution of the excited state, H- C=0 (Adrian et al., 1962) to the electronic structure and it is feasible... 

However, there are exceptions to this rule. Riegel and co-workers have already shown that Fe impurities, being injected into alkali metals, show hyperfine properties that indicate very large orbital moments close to the full atomic values (Riegel et al. 1986). This seems to be due to the weak hybridization with the host electronic states... 

S-To-type, and reports of S-T i-type CIDNP imder these conditions are very rare, even in low fields. All recent examples involve radical pairs with very large hyperfine coupling constants caused by an inorganic nucleus ( P or Sn). Even then, diffusion must favour longer dwell times around the level crossing, as is seen by the observation that low-field net CIDNP of P from the radical-pair trimethylbenzoyl/dimethoxyphosphonyl still arises to 60-70% through S-To-type CIDNP in the less viscous solvent acetonitrile, while in the more viscous solvent dioxane the contribution of this intersystem crossing pathway decreases to 20-50%. ... 

A source of the alloy SmFe7 has shown a very large hyperfine splitting of the 103-keV resonance as shown in Fig. 17.11 [69]. The magnetic field is... 

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