Imaging the Condensation and Evaporation of Molecularly Thin Films of Water with Nanometer Resolution

Abstract

The polarization force between an electrically charged atomic force microscope tip and a substrate has been used to follow the processes of condensation and evaporation of a monolayer of water on mica at room temperature. Condensation proceeds in two distinct structural phases. Up to about 25 percent humidity, the water film grows by forming two-dimensional clusters of less than a few 1000 angstroms in diameter. Above about 25 percent humidity, a second phase grows, forming large two-dimensional islands with geometrical shapes in epitaxial relation with the underlaying mica lattice. The growth of this second water phase is completed when the humidity reaches about 45 percent. The reverse process of evaporation has also been imaged.

Force measurements with the atomic force microscope: Technique, interpretation and applications

“…Often quite different dependencies of adhesion force on humidity are reported for the same system, e.g. for mica [700,706,707], and the increase of adhesion with humidity is either reported to be step-like [694,700], linearly increasing [686,708] or exhibiting a maximum at intermediate values [707,684]. These discrepancies need clarification.…”

Nanoscale dielectric microscopy of non-planar samples by lift-mode electrostatic force microscopy

“…Among them, we can cite nanoscale capacitance microscopy [1][2][3], electrostatic force microscopy (EFM) [4][5][6][7][8][9][10], nanoscale impedance microscopy [11,12], scanning polarization force microscopy [13][14][15][16], scanning microwave microscopy (SMM) [17,18] and nanoscale non-linear dielectric microscopy [19]. These techniques have allowed measuring the electric permittivity with nanoscale spatial resolution on planar samples, such as thin oxides, polymer films and supported biomembranes [2][3][4]8,10], and on non-planar ones, such as, single carbon nanotubes, nanowires, nanoparticles, viruses and bacterial cells [20][21][22][23][24][25][26][27][28][29][30].…”

Evidence of Stranski–Krastanov growth at the initial stage of atmospheric water condensation

“…1a). Under ambient conditions (25°C; relative humidity (RH) B35%), freshly cleaved mica substrate is hydrophilic and thus will inevitably absorb a heterogeneous water film (whole layer or islands of water molecules) with a thickness depending on the ambient RH 14,20 . Given this default water layer on the mica surface, graphene and MoS 2 sheets were then carefully transferred onto mica through mechanical exfoliation (Fig.…”