Influence of laser-produced plasma parameters on the deposition process: in situ space- and time-resolved optical emission spectroscopy and fractal modeling approach

The formation and dynamics of Al and Ag-Ni-Fe plasmas were studied through ICCD imaging and space- and time-resolved optical emission spectroscopy techniques. The experiments were conducted in pulsed laser deposition configuration and the surface topography and chemical composition of the obtained thin films were analyzed. For both targets, a splitting of the plasma plume was observed. Two structures with distinct velocities were analyzed and associated with different types of species: the ions were found predominantly in the fast structure while the excited species were observed mainly in the slow structure. Their different velocities were correlated to the different ejection mechanisms which lead to plasma formation. The angular distributions of the plasma front velocity were analyzed and associated with the mass of the main elements found in the plume. The excitation temperature determined for excited species presented a more uniform distribution than the one calculated for ions using the Boltzmann plot. The experimental results were described by a non-differential theoretical model which took into account the scattering probability, collision frequency and the fractality of the plasmas.