ABSTRACT
Adsorbed water plays an important role in adhesion measurements, since it is responsible for the capillary force between the A F M tip and sample surface. In particular, with muscovite mica the adsorbed water is so strongly bound to the mica surface that it is impossible to remove it by simply 'outgassing' under U H V conditions or through a gentle heating of the sample [23]. Muscovite mica is ideal for studying a variety of surface phenomena since it is an aluminosilicate that can be easily cleaved yielding an atomically planar surface. It is well known that organic ions and simple compounds are picked up by clays (similarly to inorganic ions), and surface spectroscopy studies indicate the presence of carbon on the surface of aircleaved mica [24]. The carbon is undoubtedly from organic origin, although there are evidences from surface reactivity with carbon dioxide [25]. Quartz, on the other hand, has a much rougher surface than mica, which is readily reflected in the force spectroscopy results.
