Single Atom Chemistry for Heavy Elements (Redox Reaction of Nobelium)

除mendelevium（_ Md）以外的重元素的化学性质<101>还不十分清楚。这些超重元素在整个实验中每次只有几个原子，因为它们的寿命很短，而且重离子加速器的生产率非常小。因此，必须采用快速有效的放射化学方法，使每个原子通过许多相同的反应迅速达到平衡。超重元素加速器在线化学通常采用气体喷射输送系统与后续色谱分离系统相结合的方法，本研究的目的是建立一套适合于更灵活化学处理的化学装置，并寻找一种最佳的重锕系元素在线化学条件。我们还试图通过阳离子交换色谱与α-羟基异丁酸酯流体和PbO 2氧化剂在JAERI串联加速器测量离子半径的NO3+，以揭示相对论效应对锕系收缩的影响。目前正在研制三种化学反应池（或柱）和一种用于在线测量α射线的新型液体闪烁计数器系统。

The chemical properties of heavy elements beyond mendelevium (_<101>Md) 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 online chemistry of superheavy elements.The purposes of the present study are to construct the chemical apparatus applicable to more flexible chemical treatments and to find a best condition of on-line chemistry for heavy actinides. We also attempted to measure the ionic radius of No3+ by a cation-exchange chromatography with an a-hydroxyisobutyrate fluent and a PbO2 oxidant at the JAERI Tandem accelerator, in order to reveal the influence of the relativistic effect on an actinide contraction. The development of three types of chemical reaction cells (or columns) and a new liquid scintillation counter system for on-line a-ray measurements are in progress at present.