Properties of Group Five and Group Seven transactinium elements

Thesis/Dissertation · Tue May 01 04:00:00 EDT 2001

DOI:https://doi.org/10.2172/785268· OSTI ID:785268

Wilk, Philip A. ^[1]

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1. Univ. of California, Berkeley, CA (United States); LBNL Library

The detection and positive identification of the short-lived, low cross section isotopes used in the chemical studies of the heaviest elements are usually accomplished by measuring their alpha-decay, thus the nuclear properties of the heaviest elements must be examined simultaneously with their chemical properties. The isotopes ²²⁴ Pa and ^266,267 Bh have been studied extensively as an integral part of the investigation of the heaviest members of the groups five and seven of the periodic table. The half-life of ²²⁴ Pa was determined to be 855 ±19 ms by measuring its alpha-decay using our rotating wheel, solid state detector system at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. Protactinium was produced by bombardment of a bismuth target. New neutron rich isotopes, ²⁶⁷ Bh and ²⁶⁶ Bh, were produced in bombardments of a ²⁴⁹ Bk target and their decay was observed using the rotating wheel system. The ²⁶⁶ Bh that was produced decays with a half-life of approximately 1 s by emission of alpha particles with an average energy of 9.25 plus/minus 0.03 MeV. ²⁶⁷ Bh was observed to decay with a 17 s half-life by emission of alpha-particles with an average energy of 8.83 plus/minus 0.03 MeV. The chemical behavior of hafnium, Ha (element 105) was investigated using the fast on-line continuous liquid extraction and detection system SISAK-LISSY. Hafnium was not observed in this experiment following transport and extraction. Protactinium was used as on-line test of the apparatus to determine the experimental efficiency of the entire system. Unfortunately, the amount of protactinium observed after the extraction, compared to the amount produced, was extremely small, only 2.5%. The extraction of the protactinium isotope indicated the efficiency of the apparatus was too low to observe the extraction of hafnium. The chemical behavior of oxychloride compounds of bohrium was investigated by isothermal gas adsorption chromatography in a quartz column at 180, 150, and 75 C. It was found to be less volatile than the corresponding compounds of the lighter group seven homologues, rhenium and technetium, which had been measured previously with the same apparatus. Assuming the bohrium compound to be BhO₃Cl, the evaluated standard adsorption enthalpy, and delta-Hads, of BhO₃Cl on the quartz surface was calculated from Monte Carlo fits to the volatility data to be -75 kJ/mol. The adsorption enthalpies for TcO₃Cl and ReO₃Cl are -51 and -61 kJ/mol respectively.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 785268
• Report Number(s): LBNL--47475
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
ACTINIDE
ADSORPTION
ALPHA DECAY
ALPHA PARTICLES
BOHRIUM
CHEMICAL PROPERTIES
CROSS SECTIONS
DUBNIUM
HAHNIUM
HEAVY ELEMENT
NEUTRON-RICH ISOTOPES
NUCLEAR PROPERTIES
PROTACTINIUM ISOTOPES
TRANS 104 ELEMENTS