Temporal and spatial evolution of the electronic density and temperature of the plasma produced by laser ablation of LiNbO3

Emission spectroscopy is used to determine the spatial and temporal evolution of the electronic temperature (T-e) and density (N-e) of the plasma generated by laser ablation in vacuum of a LiNbO3 target. It is found that whereas N-e (in the range of 10(16) cm(-3)) decreases by a factor of 2 as the distance to the target surface increases 10 mm, T-e (in the range 0.7-0.8 eV) only decreases 10% between 2 and 4 mm from the target to remain nearly constant for longer distances. While T-e is almost constant in time at the studied distances, N-e presents a maximum at a time delay that increases when increasing the distance to the target surface. The space-time constancy of T-e is related to a collisional decoupling of the heavy species in the plasma for distances longer than 2-4 mm. (C) 2001 American Institute of Physics.