1. KFKI Res. Inst. for Part. Nucl. Physics, P.O.B. 49, 1525 Budapest 114, Hungary
2. Lab. Chim. Nucléaire, IReS, IN2P3, CNRS, BP. 28, 67037 Strasbourg Cedex 2, France
3. Inst. of Isotope and Surface Chemistry, P.O.B. 77, 1525 Budapest, Hungary
4. Centr. Res. Inst. for Chemistry, P.O.B. 19, 1525 Budapest, Hungary
5. Lab. Mat. Minéraux, URA CNRS 428, 3 rue A. Werner, 68093 Mulhouse Cedex, France