Laser-induced metastable phases in liquids

摘要

Pulsed laser ablation at solid-liquid interfaces is gaining wide acceptance due to the production of functional nanomaterials having potential implications. The complex phenomena involved in the laser ablation process cause extreme pressure and temperature and a highly transient preferential growth of metastable phases is possible. Understanding of the nucleation phenomena of laser-produced nanoparticles in liquid is still limited and more orientated towards exploring the applicability of the nanoparticulates. The current work thus focuses on the nucleation dynamics of the high-pressure phase of TiO2 having an orthorhombic alpha-PbO2-like structure formed during pulsed laser ablation at the titanium-water interface. The nucleation time (10(-11) to 10(-8) s), growth velocity (maximum of similar to 100 nm ns(-1)) and particle statistics are calculated and compared with experimentally derived particle statistics (3-180 nm). Pulsed laser ablation in liquid is also accompanied by mechanical phenomena known as cavitation bubbles. Insight into the possible role played by cavitation bubbles in the nucleation of nanoparticulates is outlined.