Monolayers of mercaptoundecanol and mercaptoundecanoic acid were prepared on Au(111) films, immersed in aqueous solutions, and probed by frequency-modulation atomic force microscopy. The pN-order tip-surface force was observed over the monolayers as a function of vertical and lateral coordinates, together with the topography of the monolayers. The observed force distribution was modulated between adjacent OH endgroups in the mercaptoundecanol monolayer, as opposed to on top of COOH and COO(-) endgroups in the mercaptoundecanoic acid monolayer. Models of the interfacial hydrogen bond between water and the endgroups were proposed. The force distribution was insensitive to the electrolyte composition. There was no qualitative sign of tip-induced confinement of water.

An R-Al 2 O 3 (011 j 2) wafer was immersed in an aqueous KCl solution of 1 mol L -1 and observed with a frequency-modulation atomic force microscope. The tip-surface force was precisely determined as a function of the tip-surface distance. The force-distance relationship contained oscillations accompanied with an exponentially decayed, electric double layer force. The force oscillations were ascribed to liquid water layers confined over the Al 2 O 3 surface.

The interface of graphite and liquid 1-decanol was studied using frequency modulation atomic force microscopy (FM-AFM). The topography of epitaxially physisorbed decanol on the substrate was traced with submolecular resolution. The tip−surface force was monitored in the liquid as a function of the vertical and lateral tip coordinates to reveal the cross-sectional structure of the interfacial decanol. Four or more liquid layers were identified by vertically modulated force distributions. The first and second liquid layers were laterally heterogeneous, as evidenced by a force distribution that was periodically modulated along lateral coordinates. A possible structuring mechanism is proposed on the basis of energy gain by hydrogen bonding and van der Waals interactions.

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A strong ordering of solvent molecules in the solid−liquid interface of a typical and characteristic organic crystal (p-nitroaniline) is observed in state-of-the-art atomic force microscopy experiments. In the current work, we use both molecular dynamics (MD) simulations and experiments in different solvents to provide a detailed understanding of the nature of the solid−liquid interface. The strong ordering of solvent molecules at the surface of p-nitroaniline is confirmed in general, but the MD simulations point to several different possible surface reconstructions, offering different ordering of water on the surface. The calculated water density profiles and local surface hydration energies suggest a novel surface structure, which is in excellent agreement with the majority of experimental results and stands as a challenge for future diffraction techniques. Our joined theoretical and experimental study emphasizes the power of high-resolution techniques to probe the solid−liquid interface in 3D while demonstrating the importance of including systematic simulation approaches to confirm the details of the molecular structure and to increase our understanding of complex heterogeneous solid−liquid interfaces.

The molecular-scale structure of water was studied over the (101) surface of p-nitroaniline crystals using advanced atomic force microscopy. p-Nitroaniline contains two polar groups on opposite ends of the nonpolar benzene ring and presents a surface of controlled heterogeneity. The cross-sectional distribution of force applied to the tip was precisely determined and was related to the local density of the structured water. Force modulations were present on the polar end-groups and absent on the benzene ring, suggesting water localization on the polar end-groups.

Mercaptohexanol is adsorbed on gold (111) and probed in an aqueous KCl solution by frequency-modulation atomic force microscopy (FM-AFM). Two different features, dot-like and rod-like protrusions, appear in the surface topography. Laterally periodic modulation of the solution density is recognized in the tip-surface force distribution cross-sectional to the surface.A possible assembly of mercaptohexanol, in which two mercaptohexanol molecules are laid down in a rectangular (3√3) unit cell, is proposed to explain the experimental results.

The topography and solvation structure of a solution-TiO 2 interface were observed in the dark using highly sensitive, frequency-modulated atomic force microscopy (FM-AFM). The nucleation and growth of an ionic solute, KCl, in this study, were observed in constant frequencyshift topography. The force applied to the tip was determined as a function of tip-surface distance. Modulations were identified on some force curves and were found to be related to the site-specific density of water molecules.