Measurements of spin concentration in electron paramagnetic resonance spectroscopy preparation of standard solutions from optical absorption

Abstract

Abstract The detailed requirements for the accurate determination of electron spin concentration by electron paramagnetic resonance spectroscopy are examined, and the use of the dual‐sample cavity for measuring spin concentrations is reviewed. The lack of adequate solution‐phase concentration standards is examined, and a new method based on photometric titration techniques is given for determining piperidine nitroxide concentrations in polar solvents. The titration procedure is used to determine the molar absorptivity of several common piperidine nitroxides in water and in water‐methanol solutions.