In the nanosecond ablation of metals in experimental conditions typically used for LIBS, the principal mechanisms of material removal are surface normal evaporation and phase explosion.
Which of these two mechanisms is better to establish the ablation stoichiometry and to create homogeneous plasma?
I have studied the ablation of metallic targets (see my articles if you want) , what I can tell that to produce thin films without droplets you have to avoid phase explosion and to choose fluence above the threshold of evaporation. Thin films with good quality are synthesize in evaporation regime.
In phase explosion you have an homogeneous nucleations of bubbles on the surface target that lead to the formation of droplets on the thin films.
In PLD the stoichiometry is conserved generally. There are several articles proving that. YBaCu is the most cited in the litterature for congruent transfer between the target and the thin film.
For good and homogeneous thin film preparation using pulsed laser deposition technique, evaporation must be slow. In this case normal evaporation will be best. Phase explosion will be violent and can deposit bigger particles ablated from the sample. Such experiment should be performed with low laser intensity.
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