In this thesis, our attempts are to identify the presence of hydrogen by using the plasmonic properties of gold nanoparticles and selecting a hydrogen gas sensitive environment around gold nanoparticles. In the first part, gold nanoparticles were prepared by pulsed laser ablation (PLA) of gold target in DI water. PdCl2 solution with different concentration was added to the obtained gold nanoparticles colloidal solutions. X-ray diffraction (XRD) confirmed the formation of metallic gold and presence of PdCl2 phases. Transmission electron microscope (TEM) images along with X-ray photoelectron spectroscopy (XPS) revealed formation of the core-shell-like structures of Pd2 #43;/Au . After hydrogenation, TEM revealed that the core-shell morphology changes into free and XPS revealed formation of the metallic Pd phase. In fact, gold nanoparticles have a negative surface charge and absorb the Pd2 #43; ion, according to the coulomb attraction, leading to the displacement of the plasmon peak of gold to shorter wavelengths. After hydrogenation, the gold plasmonic peak shifts to longer wavelengths. With this system, a desirable detection capability for low concentrations of hydrogen (0.3% H2 in Ar) was observed. In the second part, nanoislands gold thin films were fabricated by pulsed laser deposition (PLD) method on quartz substrates at different substrate temperatures of 25, 300, 450 and 600 °C. A thin (4-5 nm) Pd film as hydrogen catalyst over-layer was sputter deposited on Au films. As the sub-layer temperature increases, the distances between the gold nanoparticles increase, and due to plasmonic coupling effect, the gold plasmon peak shifts to shorter wavelengths. After hydrogenation, the volume of palladium increases, leading to surface tension and formation of small cracks on the surface. Due to the uniformity of the surface in the 25 ? temperature sample before and after hydrogenation, it caused more changes, and led to further displacement in the gold plasmon peak and detected 0.2% H2 in Ar. Finally, in the last part of this study, plasmonic sensing of gold nanoparticles solution was investigated in the presence of PdCl2 and WO3 solution. The WO3-Pd2 #43; solution has clear color, which turns blue in the presence of hydrogen gas, and can lead to the displacement of the gold plasmon peak. Samples with different molar concentrations were made and its plasmonic sensory properties were investigated.
