The chemical properties of heavy elements beyond mendelevium (101Md) have not well been known. These superheavy elements are available in quantities of only a few atoms at a time throughout the experiments, due to their short-lives and their extremely small production rates with a heavy-ion accelerator. Therefore, rapid and efficient radiochemical procedures must be employed, in which each of the available atoms rapidly reaches equilibrium through many of the same reactions. Gas-jet transport system, combined with the following chemical separation system using a chromatographical technique, is commonly adopted for the accelerator on-line chemistry of superheavy elements.
The purposes of the present study are to make the system applicable to more flexible chemical treatments and to find a best condition of on-line chemistry for heavy actinides. Here the present status is reported for development of three types of chemical reaction cells (or columns) and a new liquid scintillation counter system for on-line α-ray measurements. We also attempted to measure the ionic radius of No³⁺ by a cation-exchange chromatography with an α-hydroxyisobutyrate eluent and a PbO₂ oxidant at the JAERI Tandem accelerator, in order to reveal the influence of the relativistic effect on an actinide contraction.