Electron relaxation rates of lanthanide aquo-cations

Abstract

Measurements of the proton relaxation rates of lanthanide (III) aquo-ion solutions show that the correlation times, which govern the proton relaxation times in these solutions, are very short (ca. 10^–13s), and are predominantly due to the electron-spin relaxation times of the cations. The variations in the relaxation rates of different Ln^III ions are discussed in terms of modulation of the different ligand-field splittings. The temperature dependence of the relaxation rates has also been studied and a relationship to the magnitude of ligand-field splittings of the different Ln^III ions is discussed.