ABSTRACT
In a first series of experiments we determined the nucleation thresholds and superheating temperatures for water on a 50 nm silver film thermally evaporated onto glass. This system was chosen for comparison with previous experiments in [54, 56], and indeed we found a nucleation temperature of (130 ± 30) °C, only slightly above the one reported in the literature. In contrast, water on conventionally polished silicon wafers (rms roughness 0.2 nm) exhibited a bubble nucleation temperature of (250 ± 30) °C in close agreement with the expected value from theory and far above that one measured on the silver film. To verify the influence of the surface roughness we patterned a silicon wafer with holes (diameter approx. 500 nm, depth approx. 40 nm, hole density approx. 0.05//xm2, for the preparation method see reference [39]). On this substrate the nucleation temperature decreased strongly to (160 ± 13) °C, close to that of the rough silver film, a clear evidence for the influence of surface roughness.
