Effect of Environmental Nuclei in Electron Spin Resonance Spectroscopy

Occasionally an electron paramagnetic resonance absorption line is accompanied by satellite lines which result from a weak magnetic dipole-dipole interaction coupling the electron spin to a neighboring nuclear spin. The satellites correspond to a change in spin state of the neighbor nucleus concurrent with the change in spin state of the electron. Expressions for the energy levels and transition probabilities for a spin-only electron coupled to neighboring nuclei are given. An example of atomic hydrogen in a glassy solid coupled to nearby protons is treated, and some of the more general consequences of the interaction are pointed out.