Plasmon-enhanced SERS detection of small molecules: Au nanoparticle-embedded TiO2 nanotubes as high Q-factor sensor substrates

We formed titania nanotube arrays containing partially embedded gold nanoparticles which exhibit extremely strong localized surface plasmon resonances (LSPR) characterized by a strong extinction coefficient and a high Q-factor. Such 3D plasmonic nanocomposites were formed by first vacuum depositing a multilayer thin film stack consisting of alternating layers of sputtered Ti and co-sputtered Ti-Au thin films followed by electrochemical anodization of the multilayer stack. When used as substrates for Surface Enhanced Raman Scattering (SERS), the synergistic action of the LSPR and high surface area nanoscaffold resulted in dramatically enhanced Raman signals for Rhodamine 6G which was used as a model probe molecule.