Surface nanobubbles as a function of gas type.

We experimentally investigate the nucleation of surface nanobubbles on PFDTS-coated silicon as a function of the specific gas dissolved in water. In each case, we restrict ourselves to equilibrium conditions (c = 100%, T(liquid) = T(substrate)). Not only is nanobubble nucleation a strong function of gas type, but there also exists an optimal system temperature of ∼35 -40 °C where nucleation is maximized, which is weakly dependent on gas type. We also find that the contact angle is a function of the nanobubble radius of curvature for all gas types investigated. Fitting this data allows us to describe a line tension that is dependent on the type of gas, indicating that the nanobubbles sit on top of adsorbed gas molecules. The average line tension was τ ≈ -0.8 nN.