Pulsed laser deposition of gold thin films with long-range spatial uniform SERS activity

Nanostructured gold thin films deposited by pulsed laser ablation show remarkable plasmonic properties and can be used as sensors based on surface-enhanced Raman scattering. The substrates are deposited onto 1×1cm2 inert supports and show a uniform morphology along that area. On the contrary, we observe a considerable dependence of the film surface morphology and plasmonic response on its position on the substrate holder. This is due to the high directionality of the species emitted in the ablation process. By keeping the substrate holder rotating in an off-axis configuration, a uniform film performance can be obtained, minimizing the differences in the plasmonic properties of the deposited films. A model of the geometry of the deposition set-up captures the details of the process and gives indications to improve the uniformity of the plasmonic properties from sample to sample. The SERS performance of the produced films was assessed with the new anti-epileptic drug perampanel.