Decompression of gas-saturated solutions does not reveal bulk nanobubbles

Bulk nanobubbles in water are expected to be unstable due to their high Laplace pressure, leading to rapid gas dissolution. Despite this, recent experimental observations and theoretical work support the existence of long-lived bulk nanobubbles, although the experimental evidence remains inconclusive, often due to insufficient pressure or contamination from existing generation methods that rely on mechanical processes or chemical mixing. We investigate bubble nucleation from a gas-supersaturated solution generated by compressing and decompressing carbon dioxide gas above a water interface, minimizing contamination. Using dynamic light scattering, we see no correlation between compression pressure and scattering intensity. Using Tyndall scattering, we observe only a fractional increase in scattering intensity within an hour of decompression from higher pressures, which we attribute to pre-existing nuclei in the form of contaminants. Our findings suggest that decompression of saturated carbon dioxide-water solutions within 1–150 bar is not a robust method for producing bulk nanobubbles.