Nature of particulate matter produced by laser ablation—implications for tandem analytical systems

Abstract

Laser ablation processes and the products thereby formed have been investigated by scanning electron microscopy and energy dispersive X-ray analysis (EDX). The structures examined consisted of ablation craters and the material mobilised into a gas stream by ablation and collected by filtration. Ablation events have also been studied by high-speed cine photography. Three types of particulate material have been identified in the ejecta. The major component from metals was spherical droplets of solidified melt-splash. With brittle materials, sharp-edged spall-breccia was also found. In both instances a minor amount of amorphous condensate from the vapour phase was present. The results of chemical analysis by EDX suggest that the ablated product might not necessarily be representative of the test material bulk. These observations account for many of the difficulties of laser ablation in remote excitation techniques and suggest methods of alleviating them.