Dynamics of Laser Ablation and Vaporization of PbZr0.54Ti0.66O3: Laser Fluence and Ambient Gas Effects

Abstract

AbstractA systematic study of the gas phase products observed from the pulsed laser vaporization of a PbZro.54Ti0.46O3target was performed as a function of laser fluence and ambient gas pressure. At low fluences, ≤0.3 J/cm2, only Pb and PbO were observed, while at higher fluences, between 0.3 - 1.3 J/cm2, neutral atomic species Pb, Zr, and Ti were detected. Small oxide molecules and atomicions were also observed. These regimes are associated with two ejection mechanisms: thermal evaporation and ablation, respectively. No direct evidence of chemical reactions was found over the gas pressure range explored (0-5 mTorr). Within the 25 cm reaction cell distance however, the addition of both inert and reactive gases greatly changed the velocity distributions of the ejected species. The decrease in velocity (energy) as a function of gas pressure was due to physical scattering and could be modeled as a pseudo-first order bimolecular collision process. The scattering rate increased linearly with the physical cross-section of the background gas and was independent of the kinetic energy of the ablated species.