CONICET | Buscador de Institutos y Recursos Humanos

Nanocomposites are nowadays one of the most promising architectures for the production of highly tunable systems. Adjusting the composite scale with optical wavelengths gives the possibility to confine and enhance the electromagnetic (EM) density field inside the structures. Among the appropriate diverse structures for this aim, photonic crystals and plasmonic structures are known as good architectures for confining light.In this work[1] we present the designed production of a nanocomposite multilayer architecture, able to control de EM density field and spatial location. For this purpose, a one-dimensional mesoporous photonic crystal (MPC) was designed and synthesized aiming to tune the band gap edges with the plasmon resonance position of the silver nanoparticles (SNP) that were infiltrated inside the multilayer. These SNP-MPC structures are expected to enhance the EM field as a dual-consequence of the periodicity of the photonic crystal architecture and the plasmon resonance. To achieve this objective, mesoporous SiO2-TiO2 multilayers were first numerically designed and then synthesized by a successive dip-coating process. The 1D-MPC were then infiltrated with Ag+, followed by mild reduction that leads to very well-defined localization of Ag NPs in the TiO2 layers. The EM field distribution was simulated to assess its spatial localization. Raman studies using an active probe (thiopyridyne) were carried out to monitor the EM field. An increase in the enhancement of the thiopyridyne Raman signals was observed in the SNP-MPC systems, which was several times higher than the one obtained with Ag NP embedded in mesoporous films with equivalent thickness (stacks) and Ag loading (Figure 1). The combined photonic-plasmonic effect observed proves that NP@MPC structures lead to an extra enhancement due to the photonic structure, and opens the gate to SERS-active substrates with increased signal.