Measurements of magnetic susceptibility in the temperature range 4 .2 -300 °K show that fer ritin is antiferromagnetic with a Neel temperature of 20°±3°K. The theory of J. S . S m a r t for antiferromagnetic exchange between iron atoms clustered in groups of two ("isolated clusters") gives the best agreement between theoretical and experimental values. The antiferromagnetic ex change constant is J / k = -4.8 (°K ). Reduced magnetic moment for J a eff= 3 .8 5 /u% is due to the transfer of two electrons from oxygen atoms to ferric atoms caused on the cation-anion-cation superexchange. Some models of superexchange are discussed. Antiferromagnetism and super exchange are possibly caused on the cubic magnetic structure of iron-oxygen micelles in ferritin.
An introduction to the method of hfs–zero-field paramagnetic resonance is given in this article and spectra of the radicals of barbituric acid, malonic acid, cyclohexane-1, 1-diacetic acid, fumaric acid, and α-alanine are shown. From these spectra the hfs-coupling-tensor values were determined.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.