J. M. Gates

Gas chemical investigation of hafnium and zirconium complexes with hexafluoroacetylacetone using preseparated short-lived radioisotopes

Abstract Volatile metal complexes of the group 4 elements Zr and Hf with hexafluoroacetylacetonate (hfa) have been studied using short-lived radioisotopes of the metals. The new technique of physical preseparation has been employed where reaction products from heavy-ion induced fusion reactions are isolated in a physical recoil separator – the Berkeley Gas-filled Separator in our work – and made available for chemistry experiments. Formation and decomposition of M(hfa)4 (M=Zr, Hf) has been observed and the interaction strength with a fluorinated ethylene propylene (FEP) Teflon surface has been studied. From the results of isothermal chromatography experiments, an adsorption enthalpy of -ΔHa=(57±3) kJ/mol was deduced. In optimization experiments, the time for formation of the complex and its transport to a counting setup installed outside of the irradiation cave was minimized and values of roughly one minute have been reached. The half-life of 165Hf, for which conflicting values appear in the literature, was measured to be (73.9±0.8) s. Provided that samples suitable for α-spectroscopy can be prepared, the investigation of rutherfordium (Rf), the transactinide member of group 4, appears possible. In the future, based on the studies presented here, it appears possible to investigate short-lived single atoms produced with low rates ( e.g. , transactinide isotopes) in completely new chemical systems, e.g. , as metal complexes with organic ligands as used here or as organometallic compounds.

Recoil-alpha-fission and Recoil-alpha-alpha-fission Chains Stemming from Element 115

Rudolph, Dirk; Forsberg, Ulrika; Düllmann, C. E.; Golubev, Pavel; Heßberger, F.P.; Khuyagbaatar, J.; Kratz, J. V.; Sarmiento, Luis; Yakushev, A.; Ackermann, D.; Andersson, L.; Block, M.; Brand, H.; Cox, D.; Derkx, X.; Di Nitto, A.; Eberhardt, K.; Even, J.; Fahlander, Claes; Gates, J. M.; Gerl, J.; Gregorich, E. K.; Gross, C. J.; Herzberg, R.-D.; Jäger, E.; Kindler, B.; Krier, J.; Kojouharov, I.; Kurz, N.; Lommel, B.; Mistry, A.; Mokry, C.; Nitsche, H.; Omtvedt, J. P.; Papadakis, P.; Runke, J.; Rykaczewski, K.; Schädel, M.; Schaffner, H.; Schausten, B.; Thörle-Pospiech, P.; Torres, T.; Traut, T.; Trautmann, N.; Türler, A.; Ward, A.; Wiehl, N. Published in: GSI Report

Element 115 Studied with TASISpec

D. Rudolph1, U. Forsberg1, P. Golubev1, L.G. Sarmiento1, A. Yakushev2, L.-L. Andersson3, A. Di Nitto4, Ch.E. Dullmann2,3,4, J.M. Gates5, K.E. Gregorich5, C.J. Gross6, R.-D. Herzberg7, F.P. Hesberger2,3, J. Khuyagbaatar3, J.V. Kratz4, K. Rykaczewski6, M. Schadel2,8, S. ◦ Aberg1, D. Ackermann2, M. Block2, H. Brand2, B.G. Carlsson1, D. Cox7, X. Derkx3,4, K. Eberhardt3,4, J. Even3, C. Fahlander1, J. Gerl2, E. Jager2, B. Kindler2, J. Krier2, I. Kojouharov2, N. Kurz2, B. Lommel2, A. Mistry7, C. Mokry3,4, H. Nitsche5, J.P. Omtvedt9, P. Papadakis7, I. Ragnarsson1, J. Runke2, H. Schaffner2, B. Schausten2, P. Thorle-Pospiech3,4, T. Torres2, T. Traut4, N. Trautmann4, A. Turler10, A. Ward7, D.E. Ward1, and N. Wiehl3,4 1Lund University, Lund, Sweden; 2GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt, Germany; 3Helmholtz Institute Mainz, Mainz, Germany; 4Johannes Gutenberg-Universitat Mainz, Mainz, Germany; 5Lawrence Berkeley National Laboratory, Berkeley, USA; 6Oak Ridge National Laboratory, Oak Ridge, USA; 7University of Liverpool, Liverpool, United Kingdom; 8Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Japan; 9University of Oslo, Oslo, Norway; 10Paul Scherrer Institute and University of Bern, Villigen, Switzerland

Extraction of niobium and tantalum isotopes using organophosphorus compounds - Part I - Extraction of 'carrier-free' metal concentrations from HCl solutions

Abstract The extraction of niobium (Nb) and tantalum (Ta) from hydrochloric acid media by bis(2-ethylhexyl) hydrogen phosphate (HDEHP) and bis(2-ethylhexyl) hydrogen phosphite (BEHP) was studied. The goal of the experiments is to find a system that demonstrates selectivity between the members of group five of the Periodic Table and is also suitable for the study of dubnium (Db, Z=105). Experiments were performed at the trace level (10-16 M Nb or Ta) using hydrochloric acid with concentrations ranging from 1−11 M and short-lived isotopes of Nb and Ta produced in nuclear reactions. When HDEHP was used as the extractant, the Nb extraction yield decreased with increasing acid concentrations above 6 M, while the amount of Ta extracted remained over 75% for all acid concentrations studied. Tantalum was found to be extracted by BEHP at acid concentrations above 6 M, while niobium was not significantly extracted. The data obtained are used as the basis to discuss the speciation of Nb and Ta under the conditions studied and to evaluate possible extraction mechanisms.