Line Positions in Isotropic Spectra

As introduced in Chapter 1, ESR spectra of radicals in liquid solution are usually interpreted in terms of a spin Hamiltonian  

As will be derived in Chapter 3, to first-order in perturbation theory, the resonant fields are  

Conversions from units of gauss into frequency or wavenumber units involves the g-value  

Nuclear hyperfine coupling results in a multi-line ESR spectrum, analogous to the spin-spin coupling multiplets of NMR spectra. ESR spectra are simpler to understand than NMR spectra in that second-order effects normally do not alter the intensities of components on the other hand, ESR multiplets can be much more complex when the electron interacts with several high-spin nuclei, and, as we will see in Chapter 3, there can also be considerable variation in line width within a spectrum. 

Naphthalene and other aromatic hydrocarbons can be reduced by one electron to produce the anion radical. The reduction can be carried out with sodium in an ether solvent or electrochemically in a polar aprotic solvent. 

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