Physics at Interfaces

Research - Dynamic Wetting


Breath figures

(together with M. Sokuler, H.-J. Butt, E. Bonaccorso)

There is a surprising asymmetry between observations of condensation and evaporation of drops. From Fick's law, it follows that the one should be the time reversed process of the other. Nevertheless, evaporating single drops volume follows a different power law than the case of a condensing field of drops. We show that the spacing of condensing drops affects the growth - or shrinkage - of drops volume in time. We demonstrate that isolated single drops volume changes faster than a drop amongst a field of similar drops. The influence of the inter-drop distance is the same in condensing and evaporating drops.


  Typical curves from multiple drop and single drop cantilever experiments:

The red dashed curve is a fit of the type V = a · tb, with b = 1.02 ± 0.08, to the multiple drop growth experiment (insert, top left). The solid black line is a fit of the same type, with b = 1.46 ± 0.12 to the single drop growth experiment (insert, bottom right). This shows the faster growth of isolated drops, compared to densely packed drops.