English abstract
Plasmonics is the study of optical phenomenon of noble metal nanostructures that interact with electromagnetic light to create surface plasmon resonance on their surface. Metallic nanostructures can be directly grown on the substrate by physical technique or colloidal metallic NPs immobilized on the substrate by chemical method. Self-organization of monolayer gold nanoparticles (AuNPs) on 3 aminopropyltriethoxysilane (APTES) functionalized glass substrate is reported. The orientation of APTES molecules on glass substrates plays an important role in the interaction between AuNPs and APTES molecules on the glass substrates. The as grown monolayers were annealed in ultrahigh vacuum and air at 600 °C and studied the surface and interface properties. The second part of this work was to employ the direct deposition of metallic NPs on the glass substrate by physical approach. DC magnetron sputtering with inert gas condensation (IGC) technique at room temperature (RT ~ 25 °C) was used to fabricate AgNPs/AuNPs on glass substrates. The as fabricated substrates were treated by post annealing below and above the glass transition temperature at 500 °C and 600 °C and studied the surface and bulk properties. In the third part of this study, silver nanoparticles (AgNPs) were deposited on soda lime glass substrates by DC magnetron sputtering with inert gas condensation (IGC) technique during in-situ annealing in an inert gas environment. The influence of in-situ annealing temperature on the surface morphology, surface composition and chemical states were investigated. Antibacterial activity of AgNPs against Escherichia coli and Bacillus cereus was also examined. For the fourth part, the exchange role of gold (Au) and silver (Ag) in bimetallic films co-evaporated onto soda-lime glass substrates with Au-Ag volume ratios of 1:2, 1:1 and 2:1 have been demonstrated. Annealing of the films above the glass transition temperature in air led to non-alloying nature of the films, silver neutrals (Ag9 and gold nanoparticles (AuNPs) on the surface, along with silver nanoparticles (AgNPs) inside the glass matrix. The higher the Au content in the film is, the more likely Ago to stay on the surface and impacts on the size distribution of AuNPs and consequently on the refractive index sensitivity measurements. The effect of substrate nature (compositions and material properties) on the formation of monometallic gold (Au), silver (Ag) and bimetallic gold-silver nanoparticles (Au-Ag NPs) by thermal annealing was carried out. Monometallic Au, Ag and bimetallic Au-Ag thin film with volume ratio of (1:1) was selected to deposit on quartz substrate by electron beam evaporation technique. Upon annealing the as prepared samples at 600 °C, monometallic AuNPs and formation of Au-Ag alloy NPs with homogeneous spherical shapes were obtained. However, monometallic Ag films could not endure at 600 °C and any AgNPs formation on the surface was not observed. The bulk refractive index sensitivity performance was studied by using alloy NPs on quartz substrate and the best LSPR performance of 61 nm/RIU was achieved.
