Pulse Radiolysis in Lanthanide Aqueous Solutions. I. Formation Spectrum and Chemical Properties of Divalent Europium, Ytterbium, and Samarium Ions

The reactions of the hydrated electrons with Eu(III), Yb(III), and Sm(III) have been investigated. Absorption spectra of transient species produced by the pulse of electrons have been obtained and assigned to the Laporte allowed transition between 4fn and 4fn−1 5d levels of the divalent ions. The excitation energy values Efd for these ions in aqueous solution are in good agreement with those found or calculated in crystal. The specific rates of reactions of Eu(II), Yb(II), and Sm(II) with OH radicals, O2, N2O, H2O2, NO2−, NO3−, BrO3−, IO3−, Cu2+ and the electron transfer reaction of Sm(II) with Yb(III) and with Eu(III) have been determined. It has been found that the order of reactivity is Sm(II) > Yb(II) > Eu(II); this order is correlated with the electrode potential E0 of divalent ions.