Formation of Agshell/Aucore Bimetallic Nanoparticles by Pulsed Laser Ablation and Chemical Reduction Methods: The Effect Green Laser Wavelength and Colloidal/Solution Concentration

The main purpose of this experimental research is to study the effects of different silver concentrations on the optical properties of bimetallic Agshell/Aucore nanoparticles. The gold nanoparticles are ablated by the PLAL technique of the gold target on the bottom of the container. The container is filled with colloidal silver nanoparticles and manufactured by chemical reduction. The colloidal solution of mixed nanoparticles is irradiated by the second harmonic of the pulsed laser Nd:YAG laser at 532 nm wavelength. The peak absorption of gold nanoparticles around 530 nm is used to transfer laser energy to nanoparticles and synthesis the Agshell/Aucore bimetallic nanoparticles. The volumetric ratio of nanoparticle solutions are the experimental variables. Bimetallic nanoparticles are distinguished by the following: X-ray diffraction pattern (XRD), spectroscopy in the range of UV-Vis-NIR and IR, Dynamic light scattering (DLS), Energy Dispersive Spectroscopy (EDS), Photoluminescence spectrum (PL) and, Fourier transform infrared spectroscopy (FT-IR). In addition, FE-SEM and TEM images are used to investigate nanoparticle size and morphology. One of the objectives of this research is the preparation of stable bimetallic systems and the study of optical properties, in order to check the reactivity of silver nanoparticles in the bimetallic system. Moreover, the shell thickness and catalytic properties of bimetallic structure with a different silver concentration is discussed. The following, dipole mode is shown in the visible area for every samples and quadrupole mode is not detected in sample with high silver concentration.