Water is an interesting matter. Water condensation involves the phase transition. At a confined space, water vapor will precipitate. Water has been extensively investigated under different environment conditions. However, in situ visualization of the dynamic transition at each given temperature for detailed insights into the structures and dynamics of water molecules is a challenge. Inspired by the natural condensation process, a thermally controlled setup was integrated into the atomic force microscope(AFM) to address the mechanism of water condensation under ambient conditions.

Generally, when the AFM tip touches a surface during imaging, it will dramatically influence the initial structures of water molecules. Therefore it is impossible for AFM to investigate the water condensation. Graphene was introduced to make it possible. Graphene, albeit only one carbon atom thick, was applied on top of water layer to not only prevent the evaporation of water molecules, but also as an ideal template for studying the structures of these ultrathin water adlayers between two solid interfaces. 

By in situ imaging the single molecular layer of water by thermally controlled AFM, the dynamic dewetting/rewetting transitions process was monitored in detail.

Experimental evidence shows that ambient water at the confined space exhibits ice-like structures at elevated temperatures. The Stranski–Krastanov model describes the complete ice-like water condensation process.

The initial stage of the water condensation in this study can potentially be utilized for understanding the boundary condition for water transport and the aqueous interfacial chemistry.

The breakthrough has been published in Nature Communications.

Read the full paper

For further information, please contact:
Postdoc Jie Song  song@inano.au.dk

or Postdoc Qiang Li Qiang@inano.au.dk

or Associate Professor Mingdong Dong dong@inano.au.dk
Interdisciplinary Nanoscience Center, Aarhus University
http://inano.au.dk/about/research-groups/bio-spm-group-assocprof-mdong/