Chemical behavior of technetium atoms recoil-implanted in metal acetylacetonates

New compounds of technetium acetylacetonates synthesized by nuclear recoil technique in our laboratory have been further studied to clarify their formation characteristics. Technetium atoms were implanted in various metal acetylacetonates using 100Ru(γ, ρ)99mTc reaction and nuclear fission of 235U. The yield of Tc(acac)3 decreased with increase of the force constant of metal-oxygen bond of the catcher system M (III) (acac)3. No such relationship could be observed for the yield of Tc (acac)2 in the catcher system M (II) (acac)2. An oxygen effect was examined in fission recoil implantation in Cr (acac)3 or Co (acac)2. Formation of 99mTcO2(acac)2 was observed by irradiation in air while it was not observed by irradiation in vacuo. These experimental results indicated the presence of its precursor 99MoO2 (acac)2 which was most probably formed by chemical reactions among Mo atom (excited by β-decay), acetylacetone ligands and oxygen. This example showed the applicability of the ''daughter tracer technique'' to the 99Mo-99mTc system. (author)