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Metal nanostructures are characterized by unique optical properties which derive from the localized surface plasmon resonance (LSPR), a collective oscillation of the conduction electrons. In particular, these nanostructures exhibit a sharp spectral absorption for incident photon frequencies resonant with the LSPR. The plasmon resonance has high intensity and it is sensitive to the environment of the nanostructures and to the coupling between them. This makes metal nanostructures of great interest for molecular sensing and several biomedical applications [1]. Understanding the dynamics that occur following absorption of photons in metal nanoparticles (NPs) is hence fundamental for many applications. The ways the different dynamical process depend on size, shape and composition of the particles are reasonably well-known. However, the interaction of the particles with their environment still requires further study to be fully understood [2]. In this work we investigated the ultrafast dynamics in Au and Ag NPs formed on silica nanowires (NWs) arrays (Fig. 1) using transient absorption spectroscopy. The silica NWs arrays are transparent in the visible to the near-UV region of the spectrum and offer a large surface area for attaching NPs, providing at the same time a macroporous support framework for an efficient interaction between the particles and the environment. All these features make the metal decorated silica NWs an optimal system for the study of the interaction with the environment and coupling between NPs. The silica NWs arrays have been fabricated via thermal oxidation of Si NWs grown using the VLS method on a quartz substrate …
Publication date: 
1 Jan 2016

L Di Mario, L Tian, D Catone, P O’Keeffe, S Turchini, F Martelli

Biblio References: 
Pages: 62
Physics and technology of nanostructured materials for photonic applications has become an important area of research that is poised to transform ongoing technologies and ultimately our everyday life in the future. Synthesis, modeling and characterization