Two-dimensional ordering of water adsorbed on a mica surface at room temperature

Monte Carlo simulations of water films on muscovite mica at room temperature reveal the formation of a strongly bound and two-dimensionally ordered water layer dependent on the arrangement and concentration of adsorbed K+ ions. This first water layer has polygonal habits in accordance with those of mica crystals, and its formation within clusters with monolayer K+ ion coverage is proposed as a prerequisite for the nucleation and growth of the polygonal water islands observed recently with scanning polarization force microscopy (SPFM) on the muscovite surface at room temperature. The saturation of this water layer in the simulation corresponds very well to the threshold for the nucleation of polygonal water islands observed in experimental studies. The saturation of the first hydration shells of the K+ ions adsorbed within clusters with monolayer K+ ion coverage results in the formation of a water film with a water-air interface of similar to 2.6 angstrom above the first water layer in very good agreement with a height contrast of 2.5 +/- 0.5 angstrom observed for polygonal water islands in SPFM experiments.