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R. Eichler, B. Eichler, H. W. Gäggeler, D.T. Jost, D. Piguet, Andreas Türler

Gas phase chemistry of technetium and rhenium oxychlorides

The chloride and oxychloride chemistry of the group 7 elements Tc and Re was investigated in order to develop an experimental approach to a gas chemical characterisation of bohrium (Bh, element 107). In thermochromatography experiments with trace amounts of ^101,104Tc and ^183,184Re the formation of one volatile compound was observed in O₂/HCl containing carrier gas, which was attributed to MO₃Cl (M = Tc, Re). From the measured deposition temperatures the adsorption enthalpies on quartz surfaces ΔH_ads(TcO₃Cl) = -51 ± 3 kJ/mol and ΔH_ads(ReO₃Cl) = -62 ± 3 kJ/mol were evaluated. The sublimation enthalpies were derived using an empirical correlation between Δ H_ads and ΔH_subl: ΔH_subl(TcO₃Cl) = 49±10 kJ/mol and ΔH_subl(ReO₃Cl) = 67±10 kJ/mol. A fast gas chemical separation technique for highly volatile compounds of short-lived isotopes based on isothermal gas solid adsorption chromatography (OLGA-principle) was developed. With a modified OLGA device, model studies with the short-lived nuclides ^106,107,108Tc and ^{169,170,174,176}Re were carried out in preparation of an experimental gas chemical investigation of bohrium (Bh, element 107). Separation times of less than 3 s were achieved. A good separation of the oxychlorides of group 7 elements from chloride and oxychloride compounds of ^152-155Er, ^151-154Ho (as models for actinide elements), ^98-101Nb, ^99-102218Po, and ²¹⁴Bi was accomplished in this chemical system.

Radiochimica Acta, Oldenbourg Wissenschaftsverlag

Print ISSN: 0033-8230
Volume: 88, 02/2000
Pages: 087

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