Dependence of Laser Ablation Produced Gold Nanoparticles Characteristics on the Fluence of Laser Pulse

Effect of laser fluence on the characteristics of gold nanoparticles (NPs) produced by laser ablation method is investigated experimentally. Five samples of gold NPs were synthesized by nanosecond pulsed laser ablation of a high purity gold plate in distilled water at five different fluences in the range of 1-3 J/cm2. Results show that in this experimental condition gold NPs are produced by nucleation of Au atoms in the plasma, generated on the target surface during the ablation process. There is threshold fluence at which absorption of laser energy by water rises significantly. Absorption of the laser energy by water leads to increase oxygen atoms in the ablation medium and formation of gold oxide NPs. By increasing the laser fluence below the threshold, size of produced NPs decreases while by increasing the laser fluence above the threshold size of produced NPs increases.