The Role of Laser Irradiance, Pulse Repetition Rate, and Liquid Media in the Synthesis of Gold Nanoparticles by the Laser Ablation Method using an Nd:YAG Laser 1064 nm at Low Energy

The synthesis of gold nanoparticles with high-purity and narrow size distribution is necessary for applications in the medical field. However, it is difficult to achieve this using chemical methods. In this study, the pulse laser ablation method using an Nd:YAG laser operated at a low-energy of 30 mJ has been successfully employed to produce gold nanoparticles with the required high purity and narrow size distribution. The role of laser irradiance, laser pulse repetition rate, and liquid media in the characteristics of the nanoparticles produced, such as shape and size distribution, were examined. In the experiment, an Nd:YAG laser beam (1064 nm, 7 ns) with a low energy of 30 mJ was irradiated on a high-purity gold plate (99.95%) immersed in a liquid medium. The results demonstrate that the average particle diameter and size distribution depended on certain parameters of the laser irradiance, the pulse repetition rate and the liquid medium used in the synthesis process. The diameters of the GNPs increased from 6.5 to 12.3 nm when the laser irradiance was increased from 12 to 20 GW/cm2. They also increased from 12.3 to 20.7 nm when the pulse repetition rate was increased from 10 to 15 Hz. In addition, the particle diameters changed in line with different liquid media used; they were much smaller for purified water (diameter of 12.3 nm) compared to ethanol (diameter of 15.0 nm). However, the shape of the GNPs was the same for these parameters; the GNPs produced by the laser ablation method were spherical. By understanding the effects of these parameters on the characteristics of the GNPs produced by the laser ablation method using a low-energy Nd:YAG laser, GNPs with specific characteristics, namely high purity and narrow size distribution, can be synthesized for specific applications in the medical field