Dipolar Broadening of EPR Spectra Due to Solute Segregation in Frozen Aqueous Solutions

Abstract

EPR spectra of Mn²⁺ and Gd³⁺ in a number of frozen aqueous solutions show that ice crystallization causes extensive segregation of solutes. The concentration of paramagnetic ions thus induced results in dipolar broadening of EPR spectra, and published spectra of frozen aqueous Mn²⁺ are reinterpreted accordingly. This segregation effect may be reduced by the addition of quantities of experimentally inert solute.