Nephelauxetic effect and hypersensitivity in the optical spectra of actinides

A concept of nephelauxetic series of systems is advanced which implies arranging all the spectroscopically studied compounds and media for a given f-ion (actinide or lanthanide) in the order of the nephelauxetic effect increase. When analysed as a whole, such a series can show trends in the degree of the f-shell interaction with the environment, as dependent on the nature of ligands and outer-sphere cations, as well as on coordination number, medium (matrix), and temperature. It is suggested that hypersensitivity series of systems can be composed for an actinide ion, which correlates with the corresponding nephelauxetic series. (orig.)