Excimer laser manipulation and pattering of gold nanoparticles on the SiO2/Si surface

Au nanoparticles were deposited onto SiO2/Si by evaporation, after which x-ray photoelectron spectroscopy (XPS) indicated some interfacial interaction between the Au and the Si. The sample was then processed by KrF pulsed excimer laser radiation (248 nm) in air, at a fluence of ∼20 mJ/cm2. Following this laser irradiation, XPS indicated the loss of substrate/nanoparticle interaction, resulting in the loss of cluster adhesion to the substrate and the formation of larger, isolated, spherical Au particles through rapid cluster coalescence. UV-visible spectral measurements indicated the absence of a surface plasmon resonance peak before irradiation, due to the small nanoparticle size (<3 nm); however, such a peak appeared at ∼550 nm after irradiation, when the particle size increased to ∼5.5 nm. Using 200-mesh transmission electron microscope grids as irradiation masks, we obtained Au nanoparticles in the unpatterned areas after irradiation. Such Au nanoparticle patterning may be used in biomolecular detector-based plasmon image-type sensors