On coordination of americium (3) in chloride melts

The spectra of Am(3) in the molten chlorides of alkaline metals and also in the metals of Cs2NaAmCl6 and AmCl3 have been studied. The melting of americium trichloride, as distinct from the Cs2NaAmCl6 complex chloride, is associated with a change of americium coordination, starting from a nonacovalent variety in the solid phase to predominantly sexicovalent variety (with the bridge bonds for Am-Cl-Am) in the melt. Analysis of the magnitude of nepheloxetic effect and intensity of ''supersensitive'' transitions suggests that the degree of the f-covalence of Am-Cl bonds in the molten chlorides of alkaline metals increases (an t deg = const) in the series (LiCl-KCl)sub(eut) approximately NaCl Am> approximately Cm