A Novel High Throughput Method for Nanoparticle Production by Atomic Vapour Deposition on a Liquid Jet

Injecting a liquid jet into vacuum, and co-depositing this with atomic vapour, various nanomaterials were synthesised. Nanoparticles of zinc oxide, copper, silver and silica were produced. The silver vapour / ethanol liquid jet system was chosen to benchmark this new synthesis method. Particles of silver in ethanol had a log-normal size distribution, with a median size proportional to the logarithm of silver concentration, over three orders of magnitude. Particles showed a plasmon resonance characteristic of silver nanoparticles. It was shown that the plasmon absorption peak shape (height to width ratio) was approximately constant for silver/ethanol samples, regardless of concentration or ageing. The solvent used had a profound effect on both the particle size, which was measured varying from 2 nm in water to 10 nm in isopropanol, but also on the plasmon shape. This ratio changed dependent on the solvent chemistry, but was largely independent to other parameters. By dissolving commercially available spheres of silica in methanol, jetting, and codeposition with silver, silica particles were decorated with silver. These particles were catalytically active, and evolved away methanol at a rate of 1.65 x 10- 7 mol g-¹s-¹. A phase of ultra-small clusters was identified in both silica and silver samples by mircoscopy and spectroscopy. In the case of silver, these were tentatively ascribed to clusters of Ag2 < n < 5. Silver deposited with pure water was highly selective of these particles. Atomic force microscopy studies of arrays of these particles on surfaces showed evidence for the co-existence of three phases of a cluster fluid. Order of magnitude diffusion rates were estimated from experimental data. Liquid like cluster arrays had diffusion rate on the order of 10-² nm²s-¹ and gas phase clusters were estimated to have a diffusion rate on the order of 1 nm²s-¹.