Laser ablation and deposition of titanium dioxide with ultrashort pulses at 527 nm

We report an experimental analysis on laser ablation and deposition of TiO<inf>2</inf> with ?300-fs, 527-nm ultrashort laser pulses. We particularly address the following: (1) the dependence of the deposition rate on the laser fluence, in high-vacuum conditions; (2) the effect of an oxygen background gas pressure on the expansion of the ablated species and on the deposition rate. Two different regimes are observed for the dependence of the deposition rate in high vacuum: The first one governed by two-photon absorption occurring close to the ablation threshold is, then, followed by the second, thermal dependence at larger fluences. The propagation of the atomic and nanoparticulate plumes produced in ultrashort laser ablation are influenced in a quite different way by the background gas pressure, which eventually reflects on the variation of the deposition rate with pressure. Moreover, it is observed that the ablated material is predominantly composed of nanoparticles (?70 %), similar to what was reported before in the case of elemental metallic targets. Finally, plume deposition results in the formation of nanoparticle-assembled films with a variation of the characteristics morphology with the background gas pressure.