(223c) Single-Step Aerosol Synthesis and Deposition of Au Nanoparticles with Controlled Size and Separation Distributions

Immobilized noble metal nanoparticles are being explored for a variety of applications where control over the particle size and separation distance on the substrate is important for performance.  A proof-of-concept is presented that Au nanoparticles can be deposited in a single step with control over the size and separation distributions using an aerosol process.  Samples were deposited with mean particle diameters in the range from 15 to 43 nm, and mean separation distances from 11 to 39 nm.  Depending on the separation distance, particles exhibited localized surface plasmon resonance (LSPR) dominated by either intra- or inter-particle resonances, as determined by uv-visible extinction spectroscopy.  Ultrathin TiO₂ shells of different thicknesses, in the range from 0 to 24 nm, were deposited on the Au nanoparticles by atomic layer deposition (ALD) to determine the sensing distance into the surrounding dielectric medium, which was estimated to be 10 nm.