Pulsed Laser Ablation of Sn and SnO₂ Targets:  Neutral Composition, Energetics, and Wavelength Dependence

We report time-of-flight mass spectrometric studies of neutral gas-phase species generated in 532 and 355 nm laser ablation of Sn and SnO 2 targets at intensities of ≈10 8 W cm -2, below the plasma threshold. A wavelength-dependent yield of Sn:Sn x O y species is observed for the oxide target, with Sn x O x ( x = 1−3) the primary products at 532 nm and atomic Sn dominant at 355 nm. Sn and Sn 2 are the primary products of Sn metal ablation, and the relative Sn:Sn 2 yield increases at the shorter wavelength. The speed distributions of neutrals ejected from the oxide target are well represented by unshifted time-transformed Maxwell−Boltzmann (MB) distributions, while those ejected from the metal target exhibit bimodal MB distributions. Typical most-probable speeds are (1−2) × 10 5 cm s -1, with peak kinetic energies (KEs) of 1−2 eV. The implications of our results for pulsed laser deposition of SnO x films will be emphasized.