TIME-OF-FLIGHT MASS-SPECTROMETRY AND COVARIANCE MAPPING TECHNIQUE INVESTIGATION OF CHARGED SPECIES EVOLUTION IN PB(TI0.48ZR0.52)O-3 LASER-ABLATION

Time of night mass spectrometry and covariance mapping technique have been used to investigate the formation of charged species in the laser ablation of Pb(Ti0.48Zr0.52)O-3 (PZT) targets. The mass spectral analysis has been carried out as a function of distance h from the target, both in high vacuum condition (10(-7) mbar) and in oxygen environment (0.2 mbar background pressure). The relative abundance of atomic, monoxide and heavy ions has been measured and discussed. In high vacuum condition the relative abundance of heavy ions is a decreasing function of the distance from the target and becomes very low, about 8%, at the deposition distances. On the contrary, the relative abundance of monatomic ions and simple oxides increases with the distance from the target. In oxygen environment the relative abundance of heavy ions does not show a monotonic trend. This is likely due to the contemporary presence of fragmentation and aggregation processes. However, at the deposition distance a significant part of the plume, about 40%, is composed of large aggregates containing Pb. Moreover, the covariance mapping analysis shows that the light species are mainly produced by dissociation of the heavy aggregates.