Summary

The combination of noble metal with ZnO nanoparticles (NPs) has attracted a great interest for the development of nanosensing and optoelectronic devices, due to their unique properties. These hybrid nanomaterials show new and enhanced optical properties that were not available for the single component NPs, boosting the performance of surface enhanced Raman spectroscopy (SERS) and surface enhanced fluorescence (SEF) applications. The scope of this research project is to assess the optical properties of noble metal - ZnO composite NPs by investigating their steady-state and time dependent optical properties following ultrafast laser excitation.

We aim to employ a simple chemical synthesis and deposition method to obtain composite core-shell nanomaterials and thin film heterostructures, avoiding thus two of the major disadvantages of these types of hybrid nanomaterials: the complicated, expensive fabrication methods and the low reproducibility of the signals due to NPs aggregation. The spectroscopic investigations will be used at each stage of fabrication to evaluate the optical properties and the photoinduced ultrafast dynamics in the single component NPs, The composite NPs and nanostructured films induced by the size, shape, and morphology of the nanomaterials.

The nanosurfaces will be functionalized with fluorophore molecules, taking into account the system properties that need to be fulfilled to ensure efficient signal enhancement, such as chemical adsorption of fluorophore molecules and the presence of hot spots in the case of SERS, as well as the optimum distance and spectral overlap between the fluorophore molecules and the composite NPs, in the case of SEF. Ultrafast spectroscopic techniques will be used to determine the energy transfer efficiency from the metallic to the semiconductor NPs and the decay rates of fluorophore molecules in the presence of the composite nanomaterials. SERS and SEF enhancement factors will be assessed.