Es break in actinide hydration structure

Yaita, Tsuyoshi

Systematic shrinkage of ionic radii is commonly observed in all elements belonging to the actinide series: for trivalent actinide ions, an electron configuration of [Rn]5 (n = 0 - 14) with one electron filling the inner 5 orbital in the order of atomic number leads to a shrinkage of the ionic radius by about 1.6 percent. Understanding such systematic changes is crucial to elucidate the effects of coordination structure, electron configuration, and relativistic effects. Here we present the first determination of the hydration bond distance of trivalent einsteinium (Es) in solution and the finding of an unexpected shrinkage of the ionic radius from Cf of about 3.7 percent, the so-called "einsteinium break".