UV-SERS monitoring of plasmons photodegradation of biomolecules on Aluminum platforms decorated with Rhodium nanoparticles

Abstract: In the search for novel nanostructured materials for UV plasmonics a limited number of choices can be done. Materials such as aluminum, rhodium, gallium and few others can be used. One of the most interesting application for UV plasmonics is Surface Enhanced Raman Spectroscopy. It can be extended to this spectral range to explore spectral properties of biomolecules that have only a small cross section in the visible spectral range. We have recently reported on a functional substrates based on nanoporous aluminum decorated with rhodium nanoparticles. This system showed an interesting behavior for UV excitation at 266 nm, with an unexpected decreasing Raman intensity for increasing rhodium nanoparticles concentrations. We proposed that this effect can be due to the difficult access to the hot spots for the molecules deposited via thermal evaporation. Here we extend this study exploring the performance of the system at another UV excitation wavelengths (325 nm) reporting on experimental results obtained using a deposition process that can bring the molecules at the hot-spots in a more efficient way. Extensive spectroscopic acquisitions, combined with 3D maps, allow to shade a more clear view on the performance of this plasmonic platform. In particular, the photodegration and the potential oxidation of biomolecules driven by the hot-electron/hot-holes produced by the rhodium nanoparticles will be reported.