Effect of laser pulse energy and wavelength on the structure, morphology and optical properties of ZnO nanoparticles

• Decreasing the laser wavelength leads to production of smaller ZnO nanoparticles.
• Increasing the laser pulse energy leads to production of smaller ZnO nanoparticles.
• In the case of larger laser pulse energy, aggregation will be decreased.
• Nanoparticles produced by 532 nm laser wavelength are more spherical.

In this work, the effects of the laser pulse energy and laser wavelength on the production of ZnO nanoparticles prepared by pulsed laser ablation of Zn metal plate in deionized water are investigated. The beam of a Q-switched Nd:YAG laser of 1064 and 532 nm wavelengths at 6 ns pulse width and different fluences is employed to irradiate the solid target in water. The ZnO nanoparticles were found to be hexagonal. The size distribution of generated ZnO nanoparticles is decreased by increasing the laser pulse energy. The rate of ZnO nanoparticles production is increased with increasing the laser pulse energy and is decreased with increasing the laser photon energy. ZnO nanoparticles were formed with different shapes depending on the laser pulse energy and laser wavelength. The bandgap energy for ZnO nanoparticles generated with 1064 nm laser pulse wavelength is calculated to be 3.59–3.89 eV.