Electrostatically stabilised nanoparticles: Self-organization and electron-beam patterning

The self-organisation of citrate- and magnesium oleate-stabilised gold nanoparticles on SiO2/Si substrates was investigated. In drop deposition, nucleation of citrate-stabilised gold nanoparticles was observed at the rim of the droplet, symmetric or multibranched dendroid gold structures were found in the area between the rim and the central part of the droplet, depending on the drying temperature. Homogeneous submonolayer nanoparticle coverage was obtained by immersion of amine-terminated SiO2/Si surfaces into a citrate-stabilised colloidal gold acidic solution. Drop deposition of magnesium oleate-stabilised gold nanoparticles onto the SiO2/Si surfaces resulted in the formation of uniformly close-packed nanoparticle arrays. Under electron beam irradiation, no apparent changes were found for monolayer films of citrate-stabilized particles, but sintering of the nanoparticles was observed in multilayer films. In contrast, coalescence of magnesium oleate-stabilised gold nanoparticle occurred in monolayer films after electron irradiation.