  We experimentally investigate the nucleation of surface nanobubbles on
PFDTS-coated silicon as a function of the specific gas dissolved in the 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
$\sim 35-40\mathrm{^oC}$ where nucleation is maximized, which is weakly
dependent on gas type. We also find that contact angle is a function of
nanobubble radius of curvature for all gas types investigated. Fitting this
data allows us to describe a line tension which is dependent on the type of
gas, indicating that the nanobubbles are sat on top of adsorbed gas molecules.
The average line tension was $\tau \sim -0.8 \mathrm{nN}$.
