Enhancement of metal-nanoparticle precipitation by co-irradiation of high-energy heavy ions and laser in silica glass

Simultaneous laser irradiation under ion irradiation is conducted to control nanoparticle precipitation in amorphous (a-)SiO2. Copper ions of 3 MeV and photons of 532 nm by Nd:YAG laser are irradiated to substrates of a-SiO2. The ion dose rate and total dose are set at 2-10 muA/cm(2) and 3.0 x 10(16)-3.0 x 10(17) ions/cm(2), respectively, and the laser power density is 0.05-0.2 J/cm(2) pulse at 10 Hz. The laser is simultaneously irradiated with ions in the co-irradiation mode, and the result is compared to that in the sequential and ion-only irradiation. Cross-sectional TEM of the irradiated specimens is conducted after measuring optical absorption spectra. In the case of co-irradiation of intense laser power and high dose (0.2 J/cm(2) pulse and 3.0 x 10(17) ions/cm(2)), Cu nanoparticles precipitate much more extensively than in the sequential irradiation, increasing both the particle diameter and the total Cu atoms in the nanoparticles. The optical absorption spectra show a surface plasmon peak of the nanoparticles. The precipitation enhancement in the co-irradiation mode suggests that the electronic energy is absorbed by the dynamic electronic states and promotes the Cu precipitation via enhancing the atomic migration. (C) 2003 Elsevier Science B.V. All rights reserved.