The Technique of Spin Resonance

ELECTRON SPIN RESONANCE OF DEFECTS 1. The Technique of Spin Resonance 

Electron spin resonance, hereafter referred to as ESR, is a sensitive method for the study of any defect which has one or more unpaired electron spins. This includes transition metal ions, F centers, molecular ions, and molecules in their triplet state. 

The characteristics of an ESR spectrum are often summarized by an expression known as the spin-Hamiltonian. This is a partial Hamiltonian, containing only spin variables, which can be used to reconstruct the spin energy levels of 

Figuie 1. ESR derivative spectrum of N atoms in irradiated KN3 showing fine structure and hyperfine structure splittings of approximately 100 gauss and 5.5 gauss, respectively. 

Finally, it should be noted that since the information that can be abstracted from ESR spectra is very detailed, the assignments of ESR spectra to various 

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