چكيده به لاتين
In this study, the production of colloidal alloy NPs of gold-silver (Ag-Au) and copper-silver (Ag-Cu) has been experimentally studied. For this purpose, in the first stage, colloidal NPs of Au, Ag, and Cu are separately produced using laser ablation method with Nd: YAG pulsed laser in distilled water, and in the second stage, specific volumes of these colloidal NPs are combined and post-irradiated by laser pulses to produce alloy NPs. In this thesis, the effect of post-irradiation time and external electric field on the properties of alloy NPs has been investigated, and the produced NPs have been studied in terms of size, shape, and optical properties.
The results of this study show that by adjusting the laser parameters such as fluence and pulse number, along with combining NPs with specific concentrations, Ag-Au and Ag-Cu alloy NPs could be produced through the irradiation of a specific combination of Au/Ag and Cu/Ag NPs, respectively. Moreover, applying an external electric field in the production process of alloy NPs significantly affects plasmonic properties and the size of NPs. Specifically, its application in the production process of Ag-Au alloy NPs has decreased the alloying time (i.e., decreased the number of pulses). The results of electron microscope images also confirm a decrease in the average size and the dispersion of the size distribution of Ag-Au and Ag-Cu alloy NPs in the presence of an electric field. In addition, UV-Vis spectroscopy results illustrate that applying an electric field blue-shifts the plasmon wavelength of the alloy NPs, while the plasmon wavelength of Ag-Au and Ag-Cu alloy NPs in the visible region can be tuned by adjusting the applied electric field. Furthermore, the alloying of Cu NPs with Ag prevent their rapid oxidation. Finally, the results in this thesis indicate that Ag-Cu alloy NPs are more stable compared with Cu NPs and are likely to have higher resistance to oxidation over time.
