UV-SERS monitoring of plasmonic photodegradation of biomolecules on aluminum platforms decorated with rhodium nanoparticles

Abstract

In the search for novel nanostructured materials for UV plasmonics, only a limited number of choices are available. Materials such as aluminum, rhodium, and gallium can be used. One of the most interesting applications of UV plasmonics is surface-enhanced Raman spectroscopy. It can be extended to this spectral range to explore the spectral properties of biomolecules that have only a small cross-section in the visible spectral range. We have recently reported on a functional substrate based on nanoporous aluminum decorated with rhodium nanoparticles. This system exhibited an interesting behavior with UV excitation at 266 nm and an unexpected decrease in Raman intensity with an increase in rhodium nanoparticle concentration. We proposed that this effect can be due to the difficult access of the molecules deposited via thermal evaporation to hot spots. Herein, we extend the above-mentioned study by exploring the performance of the system at another UV excitation wavelength of 325 nm and by reporting experimental results obtained using a deposition process that can bring the molecules to the hot spots in a more efficient way. Extensive spectroscopic data, combined with 3D maps, provided a more clear view of the performance of this plasmonic platform. In particular, the photodegradation and potential oxidation of biomolecules driven by the hot electrons/hot holes produced by the rhodium nanoparticles are reported.