Xe ion irradiation-induced polycrystallization of Ag nanoparticles embedded in SiO 2 and related optical absorption property

The Xe ion irradiation-induced structural modifications of implantation-synthesized Ag NPs were explored in this paper. Our results clearly show that Xe ion irradiation could induce transformation of crystalline Ag NPs into polycrystalline ones with various shapes. The modified Ag NPs exhibit a notable shoulder absorption band around 550 nm besides the surface plasmon resonance (SPR) peak located at about 400 nm. Reduction of the electron mean-free-path and interaction between crystallites in the formed polycrystalline NPs have been proposed to interpret the appearance of the shoulder absorption band. Moreover, our results also show that subsequent thermal annealing at 400 °C for 1h can restore polycrystalline Ag NPs to crystalline ones with spherical shape, which are nearly aligned around the end of the Ag ion range, and contribute a much narrower SPR absorption peak at 400 nm.