Electron-Spin Resonance Spectroscopy

Electron-spin resonance (ESR) spectroscopy, otherwise known as electron paramagnetic resonance (EPR) spectroscopy, is a nondestructive, noninvasive, highly sensitive and accurate analytical technique that can detect and characterize chemical species possessing unpaired electrons, i.e., paramagnetic. Soil species able to produce ESR spectra include organic free-radical moieties in humic substances (HS) and organic- and mineral-associated paramagnetic metal ions. Further, ESR labeling, trapping, and metalprobing methods are used to study the dynamics of macromolecules in soil solution, HS complexation chemistry, and ion sorption on mineral surfaces.