ION-EXCHANGE EQUILIBRIA AND STOICHIOMETRY OF COMPLEXES OF ELEMENT-104AND HAFNIUM IN HYDROFLUORIC-ACID SOLUTIONS

In bombardments of a Cm-248 + Gd-152,Gd-154,Gd-158 target with O-18 io ns, atoms of 78-s (261)104 and Hf165-169 (half-lives of a few minutes) were simultaneously produced. They were continuously on-line processe d in a Wofatit HS 36 anion exchanger column with 0.27 M HF -0.2 or 0.1 M HNO3 as the eluent. The elution time and then the distribution coef ficients, K-d, of fluoride complexes of the elements were evaluated fr om the numbers of the short-lived nuclei that decayed in the column as well as those which survived. Actually, long-lived descendants rather than the mother activities were detected, which is a distinctive feat ure of the employed technique. In particular, a total of more than 120 decays of Es-253 descending from (261)104 were registered in the thre e experiments performed. The obtained K-d values for element 104 and H f are nearly equal. From measurements of K-d versus the concentration of HNO3, the ionic charge of the element 104 complex is -1.9+/-0.2, th us pointing to [104]F-6(-2) as the chemical state of the element.