Correction orbital hyperfine

Since the nuclear magnetic moments are small in magnitude, the corrections arising from the commutator relations can be neglected. However, it is convenient to retain k0 as a convergence factor so that we arrive at the orbital hyperfine interaction in the form... 

The internal dipolar contribution yields the electron-electron spin-orbit hyperfine correction... 

A contribution from the nuclear dipolar field AN( i) = (fio/4n)rN](jlN x rNi) yields the spin-other orbit hyperfine correction... 

It is well-known that the hyperfine interaction for a given nucleus A consists of three contributions (a) the isotropic Fermi contact term, (b) the spin-dipolar interaction, and (c) the spin-orbit correction. One finds for the three parts of the magnetic hyperfine coupling (HFC), the following expressions [3, 9] ... 

The naphthalene anion radical spectrum (Figure 2.2) provided several surprises when Samuel Weissman and his associates1 first obtained it in the early 1950s at Washington University in St. Louis. It was a surprise that such an odd-electron species would be stable, but in the absence of air or other oxidants, [CioHg]- is stable virtually indefinitely. A second surprise was the appearance of hyperfine coupling to the two sets of four equivalent protons. The odd electron was presumed (correctly) to occupy a it molecular orbital... 

However, if this simple zwitterionic model were correct, one would need to consider which of the two elg levels contains the unpaired electron. The negative oxygen atom would presumably repel the paired electrons which would thus occupy the antisymmetric orbital, leaving the unpaired electron to half-fill the symmetric level. Thus negative hyperfine couplings of about 1 9 G for o- and m-protons, and 7-5 G for the p-proton are predicted. 

The fourth and last terms in (11.49) are spin-orbit distortion corrections to the spin-rotation and Fermi contact interactions. The hyperfine and quadrupole terms in this Hamiltonian refer to the 14N nucleus. 

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