Study of the fragmentation phenomena of TiO2 nanoparticles produced by femtosecond laser ablation in aqueous media

• Two step laser assisted TiO2 nanoparticle production in an SDS solution using a femtosecond laser.
• TiO2nanoparticles with controlled size and morphology in liquid.
• An interesting plasmonic effects in UV region.

Since last decade, Pulsed Laser Ablation in Liquid (PLAL) has become an increasingly important technique for the production of the nanoparticles (NPs) since it usually provides high purity nanoparticle systems. This paper reports on the production and fragmentation of titanium oxide TiO2 nanoparticles by pulsed laser ablation of a titanium target immersed in Sodium Dodecyl Sulfate (SDS) solution using an ultrafast Ti:Sapphire laser. After the production of TiO2 nanoparticles for 30 min of laser irradiation, second harmonics of the laser wavelength are re-applied for different energies (180,120, 60 µJ) to SDS solution containing TiO2 colloids in order to fragment relatively large pieces to obtain smaller ones. It was found that size of nanoparticles after the treatment is independent of the initial characteristics of colloids, but depends strongly on laser parameters especially pulse energy and on the presence of chemically active species in the solution. It was reported that particle size and size distribution range can be decreased using second harmonics of Ti:Sapphire laser wavelengths by using different values of energy. Re-irradiation process at average energy value of 180 μJ decreased average particle size from 185 nm to 110 nm. Characterization of the NPs was studied by applying various techniques such as UV–visible (UV–vis.), Transmission Electron Microscope (TEM), Dynamic Light Scattering (DLS) and Fourier Transform Infra-Red (FTIR).