Craters and amount of ablated material

Ruby and Nd YAG lasers produce craters ranging from 1 to 500 pm in size. The craters are usually wider than deeper and exhibit overlapping rough materials at the edge suggestive of thermal effects. 

The rapid increase in crater depth above the threshold irradiance for phase explosion correlates with a significant increase in signal intensity. The ratio of crater volume to signal intensity, which represents the entrainment efficiency, remains the lowest at laser irradiances slightly above the phase explosion threshold. Such a ratio, however, increases at irradiances well above the threshold ( 10 W/cm ). 

Particles differ in diameter and shape. Spherical particles are formed from molten material. Angular fragments are ejected directly from the surface. Dimensions can be up to 10 pm, which is too large to ensure efficient transport and thorough volatilization in the subsequent plasma, ffame or electrothermal atomizer. 

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