Effect of femtosecond Ti:Sapphire laser wavelengths on plasmonic behaviour and size evolution of silver nanoparticles

Production of the nanoparticles (NPs) by laser ablation from a solid target emerges as an alternative physical method. When a solid target is irradiated by a femtosecond laser, radiation energy is absorbed by the material, followed by, ejection of atoms/small atomic clusters. In this study, the plasmonic behaviour and size variation of silver nanoparticles produced in an aqueous solution of sodium dodecyl sulfate (SDS) has been investigated using an ultrafast Ti:Sapphire laser. After the production of silver nanoparticles in 30 min of laser irradiation, the fundamental and the second harmonics of the Ti:Sapphire laser wavelengths are re-applied for different times (10, 50, 90 min) to diluted SDS solution which contains silver colloids in order to investigate the effect of laser wavelength on agglomerated particles, particle size and shift of the absorption wavelength towards UV. We report that particle size and particle size distribution range can be decreased for both Ti:Sapphire laser wavelengths. Due to the absorption spectrum of the silver nanoparticles, at the end of the 90 min re-irradiation process, sizes of the nanoparticles decreased to 11 nm and 22 nm for 400 nm and the 800 nm laser irradiations, respectively. Depending on the variation of the nanoparticle sizes, in the case of the 400 nm laser irradiation, the shift towards UV is more than the shift produced by 800 nm laser irradiation. The experimental results show that the aggloremation and nanoparticle sizes can be reduced by the second application of the laser beam. (C) 2011 Elsevier B.V. All rights reserved.