Extended experimental and theoretical analysis of the hyperfine structure in the ground multiplets of Pu I and Pu II

New measurements of the hyperfine splittings of the levels of the lowest 8,⁶F terms in the configuration 5f⁶7s of Pu ii have been obtained by use of three different high-resolution methods. These new data allow a detailed theoretical analysis of the hyperfine structures. Eigenfunctions of the levels of 5f⁶7s, in intermediate coupling, are first obtained by diagonalization of the whole energy matrices, after which the values of the $a_f^{01},a_f^{12},a_f^{10}$ and $a_s^{10}$ hyperfine-structure parameters are determined by a least-squares optimization. Analogous studies of the energies and of the hyperfine structures were done on the 5f⁶7s² configuration of Pu i.