Plume dynamics from UV pulsed ablation of Al and Ti

Pulsed laser ablation of Al and Ti with a < 3.3 J/cm(2) KrF laser and Ar background pressure of up to 1 Ton was performed to study the ablated plume. Mass loss experiments revealed the number of ablated atoms per pulse increases by similar to 30% for Ti and similar to 20% for Al as pressure decreases from 1 Ton to vacuum. Optical emission imaging performed using a gated ICCD revealed a strong dependence of shock front parameters, defined by the Sedov-Taylor blast and classical drag models, on background pressure. Spatially resolved optical emission spectroscopy from Al I, Al II, Ti I, and Ti II revealed ion temperatures of 10(4) K that decreased away from the target surface along the surface normal and neutral temperatures of 10(3) K independent of target distance. Comparison between kinetic energy in the shock and internal excitation energy reveals that nearly 100% of the energy is partitioned into shock front kinetic energy and similar to 1% into internal excitation.