Gas-phase isothermal chromatography with short-lived technetium isotopes

In order to study the gas-phase chemical behavior of transactinides, an on-line isothermal chromatography apparatus has been developed and applied to separate short-lived technetium isotopes in the form of TcO3 from fission products. The fission products from a 252Cf source were continuously and rapidly transported through the capillary to the isothermal chromatography apparatus using the N2/KBr gas-jet techniques. Volatile oxide molecules were formed at the reaction zone kept at 900 C since a trace amount of oxygen existed in the N2 carrier gas. With the new developed isothermal chromatography apparatus, a selective separation of Tc from fission products was achieved. After isothermal chromatographic separation, 101,103,104,105,106,107,108Tc were dominantly observed together with their Ru daughters in the γ-spectrum, The chemical yields of 101Tc, 104Tc and 105Tc isotopes with longer half-lives are about 55-57%, and those of 103Tc, 106Tc, 107Tc and 108Tc isotopes with shorter half-lives dropped down to 25-28%. The adsorption enthalpy of the investigated compounds on quartz surfaces was determined to be - 150 ± 5 kJ/mol by fitting the measured retention curves with a Monte Carlo model. The observed species of technetium oxide is attributed to TcO3, which is in good agreement with previous experimental results. That means our system worked properly and it can be used to investigate the gas-phase chemical behavior of transactinides. (orig.)