Electron Spin Resonance in a Gamma-Irradiated Single Crystal of Mercaptosuccinic Acid

Abstract

The four most intense resonances in the ESR spectrum of a γ‐irradiated single crystal of mercaptosuccinic acid are each shown to be due to the same free radical which has four different orientations in the crystal. By analysis of the anisotropy in the spectroscopic splitting factor the principal values of the g tensor were found to be 2.003, 2.026, and 2.054. It is believed that the free radical HOOC–CH₂–HCS–COOH is responsible for the observed resonance. The model of Kurita and Gordy in which the electron spin density is concentrated in a nonbonding 3p orbital of the sulfur atom successfully accounts for the basic features of the anisotropy of the g tensor.