  The growth of surface plasmonic microbubbles in binary water/ethanol
solutions is experimentally studied. The microbubbles are generated by
illuminating a gold nanoparticle array with a continuous wave laser. Plasmonic
bubbles exhibit ethanol concentration-dependent behaviors. For low ethanol
concentrations (f_e) of < 67.5%, bubbles do not exist at the solid-liquid
interface. For high f_e values of >80%, the bubbles behave as in pure ethanol.
Only in an intermediate window of 67.5% < f_e < 80% do we find sessile
plasmonic bubbles with a highly nontrivial temporal evolution, in which as a
function of time three phases can be discerned. (1) In the first phase, the
microbubbles grow, while wiggling. (2) As soon as the wiggling stops, the
microbubbles enter the second phase in which they suddenly shrink, followed by
(3) a steady reentrant growth phase. Our experiments reveal that the sudden
shrinkage of the microbubbles in the second regime is caused by a depinning
event of the three phase contact line. We systematically vary the ethanol
concentration, laser power, and laser spot size to unravel water recondensation
as the underlying mechanism of the sudden bubble shrinkage in phase 2.
