A Study on Formation and Growing Processes of the Colloids Containing Long-Lived Radionuclides by Means of Laser Induced Photoacoustic Spectroscopy

用直线加速器产生的韧致辐射辐照过铁酸盐水溶液，研究了二氧化碳水合物胶体的辐射分解形成。透射电子显微镜显示胶体的大小分布在50-130 nm之间。用色散X射线光谱分析确定了胶体的组成。电子衍射分析表明，该胶体为非晶态结构。胶体的产率受溶液中溶解气体的影响很大。在氧气和一氧化二氮饱和的溶液中，没有形成胶体，而在Ar饱和的溶液中，有90%的Tc是胶体。在作为二氧化锶胶体前体的Tc(IV)物种的形成过程中，发现水合电子在高铁酸盐离子的还原过程中起着重要作用，随后TC(VI)和Tc(V)发生歧化反应。用激光诱导光声光谱研究了硫化锶胶体的形成和生长过程。对硫化锶胶体颗粒的光声信号分析表明，胶体颗粒的尺寸是通过硫化锶沉积在颗粒表面而不是通过胶体颗粒的凝聚而增加的。

Radiolytic formation of the colloids of technetium dioxide hydrate was investigated by irradiation of aqueous pertechnetate solutions with bremsstrahlung generated from a linear accelerator. Transmission electron microscopy revealed the size distribution of the colloids between 50 and 130 nm. The composition of the colloids was confirmed by dispersive x-ray spectrometry. An amorphous structure of the colloids was found by electron diffraction analysis. The yield of the colloids was strongly affected by dissolved gases in solutions. In the solutions saturated with oxygen gas or nitrous oxide gas, no colloids were formed, while 90 % of Tc was found as the colloids for the Ar-saturated solutions. In the formation of Tc(IV) species as a precursor of technetium dioxide colloids, it was found that hydrated electrons played an important role on the reduction processes of pertechnetate ions followed by successive disproportionation reactions of Tc(VI) and Tc(V).Laser induced photoacoustic spectroscopy was applied to a study on the formation and growing processes of technetium sulfide colloids. Analysis of the photoacoustic signals from technetium sulfide colloid particles revealed that the colloid particle the size of colloid particles increased by deposition of technetium sulfide on the particle surfaces, not by coagulation of colloid particles.