Plasmonic properties Modeling of Nanoparticle (Au, Ag) -mesoporous oxide thin films (TiO2 and SiO2)

SANCHEZ, VERONICA; MARTINEZ, EDUARDO; MARTINEZ RICCI, MARIA LUZ; SOLER-ILLIA, GALO

Santiago de Chile

Congreso; Pan-American Advanced Studies Institute (PASI) 2012; 2012

Mesoporous thin films (MTF) are synthesized in our laboratory by a sol-gel technique: these films constitute mesostructures with pores size in the range of 2-10nm. MTF provide a matrix environment where to synthesize and immobilize noble metal nanoparticles (NP). As a result, a nanocomposite material -nanoparticles included in a mesoporous thin films (NP@MO2)- is obtained with plasmonic properties that depend on the amount of NP inmersed in the MTF and the specific oxide that constitutes the matrix. To characterize the optical response of these materials ellipsometric and UV-Visible spectroscopic measurements are employed.  The first one provides the dielectric function of the material and the film thickness while the second one measures the light transmission through the film. Both methods can be compared with each other and their measurements can be selected individually to be modeled.In order to model the NP-MTF plasmonic properties the classical electromagnetic theory is employed at the cuasielectrostatic approximation using on one hand the Discrete Dipole Approximation (DDA) model implemented at the DDscat program and on the other hand the effective medium theory. The former could be directly related to the spectroscopic measurement and the latter to the ellipsometric characterization. The analysis of Ag@SiO2, Ag@TiO2 and Au@TiO2 through experimental characterization and classical modeling, is reported in this work. The following graphics represent part of the study done on Ag@SiO2 .