Ablation of BaTiO3 in a gas pressure: plasma and film optical properties

Space-resolved real-time emission spectroscopy and in situ reflectance measurements during film growth are used to characterize the plasma expansion dynamics and the refractive index of films produced by laser ablation of BaTiO3, respectively. The refractive index of the films remains nearly constant when increasing the gas pressure up to a pressure threshold above which it increases sharply, similar results being obtained either in oxygen or argon. This behavior is correlated to the changes observed in the plasma expansion dynamics; the results being discussed in terms of the dependence of the length of the plume on the gas pressure and the change of the species dynamics from an expansion regime to a diffusion one for distances close to the plume length.