Nanoscale resolution of thin film profile of the evaporating water droplet induced by substrate heating

The water film morphology near the triple phase contactline during the evaporation is investigated experimentallydue to importance of the thin film region in partial wettingevaporation regime. The state-of-the-art tapping-modeatomic force microscopy (TM-AFM) is used to get the highresolution film profile goes down to 2 nm from the contactline. The substrate was heated by PI film heater. Thereceding speed was less than 25 nm/s. The dominant resultsindicate that the film profile goes down straightly to thesurface till 2 nm from the substrate. However, smallbending has been observed below 20 nm, occasionally. So,it can be claimed that for low evaporation rate themicroscopic contact angle equals to the optically detectablemacroscopic contact angle. This result can be used tosimplify the heat transfer modeling in partial wettingevaporation.