Ion-induced elongation of gold nanoparticles in silica by irradiation with Ag and Cu swift heavy ions: track radius and energy loss threshold

Abstract

Systematic investigations of the energy loss threshold above which the irradiation-induced elongation of spherical Au nanoparticles occurs are reported. Silica films containing Au nanoparticles with average diameters of 15-80 nm embedded within a single plane were irradiated with 12-54 MeV Ag and 10-45 MeV Cu ions at 300 K and at normal incidence. We demonstrate that the efficiency of the ion-induced nanoparticle elongation increases linearly with the electronic energy transferred per ion track length unit from the energetic ions to the silica film. Ion beam shaping occurs above a threshold value of the specific electronic energy transfer. Three relevant regions are identified with respect to the original size of the Au nanoparticles. For 15 and 30 nm diameter particles, elongation occurs for electronic stopping power larger than 3.5 keV nm(-1). For Au nanoparticles with 40-50 nm diameter an electronic stopping power above 5.5 keV nm(-1) is required for elongation to be observed. Elongation of Au nanoparticles with 80 nm diameter is observed for electronic stopping between ∼ 7-8 keV nm(-1). For all combinations of ions and energies, the ion track temperature profiles are calculated within the framework of the thermal spike model. The correlation between experimental results and simulated data indicates a thermal origin of the increase in the elongation rate with increasing the track diameter.

Synthesis of cobalt nanoparticles on Si (100) by swift heavy ion irradiation

“…This could lead to significant atom displacement and mass movement, even to the surface [14]. The resulting changes in the target depend on the systems being considered (ion mass as compared to the target, ionic charge, incident energy, and the electronic structure of the target - whether metal, semiconductor, or insulator), varying from amorphization to crystallization and shape change of implanted targets in the direction of the ion beam [15,16]. In the case of metal films, due to the delocalized electronic configuration, models of energy transfer have had to consider electronic thermal spike effects as well [17-19].…”

Si Nanocrystal Arrays Created in SiO2 Matrix by High-Energy Ion Bombardment

“…Integrally, these effects result in general ordering of nanocrystals along ion tracks. The same processes proceed in the case of metal inclusions embedded in an insulator matrix and, as it was shown recently (Mishra et al, 2007;Giulian et al, 2010;Dawi et al, 2011;Kumar et al, 2011), irradiation with sufficiently high ion fluences and energies provides a means for forming long wire-shaped nanoparticles in ion tracks. Table 3.…”

Microstructural and plasmonic modifications in Ag–TiO2 and Au–TiO2 nanocomposites through ion beam irradiation

“…3) after irradiation up to a fluence of about 1 × 10 13 ions/cm 2 . Despite the fact that condition for elongation (particle size ≥ track size) holds true, no elongation of nanoparticles under ion irradiation has been observed and it is probably due to absence of a latent track formation mechanism because of the semiconducting nature of the matrix as compared to insulating matrices (e.g., SiO 2 ) in which ion tracks are usually formed [20,28–29 41]. …”