On-Demand Bulk Nanobubble Generation through Pulsed Laser Illumination

We demonstrate the temporally and spatially controlled nucleation of bulk nanobubbles in water through pulsed laser irradiation with a collimated beam. Transient bubbles appear within the light exposed region once a tension wave passes through. The correlation between illumination and cavitation nucleation provides evidence that gaseous nanobubbles are nucleated in the liquid by a laser pulse with an intensity above 58  MW/cm². We estimate the radius of the nanobubbles through microscopic high-speed imaging and by solving the diffusion equation to be below 420 nm for ∼80% of the bubble population. This technique may provide a novel approach to test theories on existence of stable bulk nanobubbles.