Nanopatterning and plasmonic properties of plasma sputtered gold on diatom frustules

Abstract

Bio-silica nanostructures from diatoms (called frustules) featuring plasmonic gold nanoparticles (NPs) are elaborated using two methods based on plasma sputtering of gold. The first investigated method uses a thermal treatment to induce the thermal dewetting of a plasma sputtered gold layer on the diatom frustules. The second method first consists of coating the frustules with polyethylene glycol before sputtering gold on these frustules. For both methods, the amount of gold appears to be a key parameter regarding the final obtained layer, which can either be nanostructured by cavities or consist in individual gold NPs. For an amount of sputtered gold equivalent to form a 5 nm thick layer, both methods allow obtaining diatom frustules covered by gold NPs with a size around 20 nm and a narrow size distribution. The UV-visible characterization of the diatom frustules featuring gold NPs highlights a plasmon extinction band in agreement with individual gold NPs with a size below 25 nm.

MRT Letter: High resolution SEM imaging of nano‐architecture of cured urea‐formaldehyde resin using plasma coating of osmium

“…) varied greatly in size (5.612–34.708 nm size range; standard deviation 6.877). According to a recent study (Romann and Einarsrud, ) the size of gold particles was around 20 nm, within a narrow size range, in a 5‐nm thick film of sputtered gold. In our work, larger size range is likely to have resulted from coalescence of particles on account of greater sputtering time of 5 min allowed within the usual sputtering time range of 3–5 min in SEM work.…”