Explosive plasmonic bubbles in locally superheated liquid

Microbubbles forming around liquid-immersed plasmonic nanoparticles under resonant continuous wave laser irradiation are of great interest in numerous applications, ranging from micro/nanomanipulation and biomedical diagnosis to solar energy harvesting and catalytic reactions. Using ultra-high-speed imaging the nucleation and the initial phase of plasmonic bubbles evolution have been revealed. After some delay time after the beginning of laser irradiation, a bubble explosively grows, up to a maximal radius of 100 microns, and then collapses within 20 μs. The maximal bubble size remarkably increases with decreasing laser power, as then the delay time prior nucleation increases, leading to more total deposited energy. The delay time depends on the gas content of the liquid, as dissolved gas clusters may act as centers of nucleation and, therefore, facilitate bubbles formation, leading to shorter delays and lower liquid superheating. After the collapse of the initial bubble much smaller oscillating bubbles appear, with typical timescale up to 10 ms. Only then earlier reported vaporization dominated and diffusion dominated phases take over and the bubble stabilizes and steadily grows.