First Ionization Potentials of Heavy Actinides

by Tetsuya K. Sato

Thursday 9 Jun 2016, 15:00 → 16:00 Europe/Zurich

26-1-022

We successfully measured the first ionization potential (IP1) of lawrencium (Lr, Z = 103) using a surface ionization method [1]. The result suggests that Lr has a loosely-bound electron in the outermost orbital. In contrast to Lr, nobelium (No, Z = 102) is expected to have the highest IP1 among the actinide elements owing to its fully-filled 5f and the 7s orbitals; due to the similarity of heavy actinides to heavy lanthanides, it is expected that the IP1 value of heavy actinoids would increase monotonically with filling electrons up in the 5f orbital like heavy lanthanoids. Recently, we have ionized and mass-separated 257No 251Md and 249Fm, and successfully determined their IP1 values. The obtained experimental results are in good agreement with the relativistic coupled cluster calculations as well as with earlier predictions. Details of the experiments and results will be given in the presentation.

[1] T. K. Sato, et al., Nature 520 (2015) 209-211.