GUIDELINES FOR INTERPRETING ELECTRON SPIN RESONANCE SPECTRA OF PARAMAGNETIC SPECIES ADSORBED ON SURFACES

Electron spin resonance (ESR) spectroscopy of paramagnetic solids and surfaces is discussed from the standpoint of the various kinds of information which ESR can provide, and how molecular structure theory is used in extracting this information from the observed spectra. The following topics are discussed: (1) Determination of magnetic constants, such as the electronic g-factors and nuclear hyperfine structure (hfs) constants, from the complex ESR lines of magnetically anisotropic molecules which are randomly oriented in polycrystalline or amorphous samples. (2) Qualitative and semiempirical theories of the electronic g-factors and hfs constants, which relate these quantities to the electronic structure of the paramagnetic species, its interaction with the surrounding solid or surface, and its ability to rotate or reorient about various molecular axes. (3) Spin-lattice relaxation with emphasis on its role in determining ESR line widths and the observability of ESR in a given system. © 1968.