Formation of nanoscale water bridges

The water bridges provide stability to sand castles, act as transport channels for dip-pen nanolitography and increase adhesion and friction in micro- and nano- devices such as MEMS. The kinetics of capillary~condensation and growth at the nanoscale is studied here using friction force~microscopy and molecular dynamics calculations. At 40{\%} relative humidity we find that the meniscus~nucleation times increase from 0.7 ms up to 4.2 ms when the~temperature decreases from 332 K to 299 K. The nucleation times grow~exponentially with the inverse temperature 1/T obeying an Arrhenius~law. We obtain a nucleation energy barrier of 7.8*10\^{}{\{}-20{\}}$\sim $J~and an attempt frequency ranging between 4-250$\sim $GHz, in excellent~agreement with theoretical predictions. These results provide direct~experimental evidence that capillary condensation is a thermally~activated phenomenon.