Laser ablation in water: A route to synthesize nanoparticles of titanium monoxide

Laser ablation of a solid target material in a liquid offers a direct, quick and easy method for nanoparticles synthesis. Titanium monoxide (and especially in the disordered cubic phase) is a material difficult to synthesize because it requires long annealing times or quenching from high temperatures and it is usually formed in the form of irregular shape chunks. In this Letter we report the synthesis of titanium monoxide nanoparticles (disordered phase) by laser ablation of a bulk titanium metal target in deionized water (picosecond laser source: 10.4 ps, 1064 nm, 50 kHz). Nanoparticles with sizes from ∼2 up to ∼200 nm were observed to be formed in the colloidal solutions. Their size distribution follows log-normal function with statistical median diameter of ≈10 nm. The synthesized nanoparticles exhibit an optical absorption edge which extends in the visible range of the spectrum (at ∼600 nm, energies ∼2 eV).