Irradiation-Induced Metal Nanoparticles in Room-Temperature Ionic Liquid

摘要

Metal nanoparticles were prepared with γ-ray and accelerator electron beam irradiation in the l-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide (BuMeIm~+Tf_2N~-) roomtemperature ionic liquids. As for Au nanoparticles yielded in this investigation, the γ-ray irradiation made the particle size smaller compared to that by the accelerator electron beam irradiation. It is interesting to note that the nanoparticles prepared in this article were very stable although the surface was not covered with a stabilizing agent, which is usually employed so as to prevent aggregation. Similarly, other metal nanoparticle productions such as Ag, Cu, Mg, Al, Zn, and Fe were also investigated by means of the accelerator electron beam irradiation. In addition, some RTILs with Au nanoparticles yielded by the irradiation experiment showed fluorescent behavior under ultraviolet irradiation of 365 nm. It implies that the RTILs contain Au nanoparticles as well as Au clusters that cannot be observed by a common TEM system. In this study, we also found that the Si wafer, on which NaAuCl_4·2H_2O-added RTIL was spread, has distinctive two-dimensional Au microstructure crystals on the surface after the accelerator electron beam irradiation.