Hollow Particles Formed on Laser-Induced Bubbles by Excimer Laser Ablation of Al in Liquid

Herein we show how the unique temporal and thermal events occurring during the pulsed excimer laser ablation of an Al target in water result in hollow Al2O3 micro/nanoparticles with smooth surfaces and an amorphous structure. We demonstrate that the hollow particles are formed on laser-induced bubbles from laser ionized/evaporated liquid during the ablation. The fabrication of hollow particles can be improved by the addition of ethanol to the water, and the particles contain crystalline Al. Our work and the associated mechanism represent a new paradigm to fabricate hollow particles directly from bulk material; that is, the excimer laser ablation produces nanoclusters from the target and bubbles from the liquid, and the bubble interfaces trap the nanoclusters, resulting in the formation of hollow particles.