SURFACE PLASMON ON METAL NANOPARTICLES

The surface plasmon response of silver nanoparticles (AgNPs) was studied for different shapes, sizes and physical environments like stabilized materials.

For this purpose, we synthesized two types of silver nanoparticles: nanospheres and nanocubes. First, silver nanospheres decorated by phototherapy dye molecules were synthesized in a one-step synthesis. The morphologies and structures of the nanoparticles were characterized by transmission electron microscopy, UV-visible spectroscopy and X-ray diffraction. The results indicated that spherical silver nanoparticles were obtained with narrow size distributions and different average sizes of 10, 50 and 100nm. The surface plasmon resonance peak was found between 390 and 450nm. Second, silver nanocubes of highly monodispersed 30nm stabilized by PVP were synthesized and characterized by UV-visible spectroscopy, TEM and SEM. The nanocubes were found to have two plasmon modes which match the two symmetry modes of the cube. The UV-visible spectroscopy peaks were found at 410nm and at 355nm. The smaller the nanocubes were, the more blueshifted the peaks became.

Significant shifts in the peak position of the surface plasmon resonance associated with the nanoparticles were observed in both cases.