Specific detection of interactions between uncharged surfaces in differentsolvents: high-resolution imaging by chemical force microscopy

The detection of hydroxyl-groups by chemical force microscopy is investigat ed in two contrasting solvents: water and hexadecane. Gold-coated cantileve rs were chemically modified in a defined way by self-assembly monolayers (S AMs) formed by mercapto-undecanol. The samples employed consisted of ultraf lat gold surfaces terminated by hydroxyl- and methyl-groups. Both surface t erminations were present on the sample surface in a well-defined pattern ob tained by micro-contact printing (mu CP). High-resolution lateral force mic roscopy (LFM) was conducted in both solvents. These LFM measurements were c omplemented by measurements of the adhesion forces on the same substrates. In contrast to water, the empolyment of hexadecane, it enables specific det ection of hydroxyl-groups and clear interpretation of the friction contrast .