SCANNING-TUNNELING-MICROSCOPY OF VARIOUS ALKANOLS AND AN ALKANETHIOL ADSORBED ONTO GRAPHITE

Scanning tunnelling microscopy has been used to image monolayers of oc tadecanol, octadecanethiol, docosanol, hexacosanol and triacontanol ad sorbed onto graphite under ambient conditions. These studies confirm t he 'herringbone' and 'parallel' packing room-temperature structures ob served previously for octadecanol and triacontanol, respectively. Adso rbed layers of docosanol and hexacosanol have been imaged for the firs t time. Docosanol was found to form monolayers containing both 'herrin gbone' and 'parallel' oriented dimers, giving rise to complex domain s tructures and complex domain boundaries. Hexacosanol has been shown to be adsorbed exclusively in the 'parallel' packed structure. A new typ e of sub-domain structure has been observed in certain triacontanol mo nolayers. Successive scans of triacontanol monolayers show evidence fo r the motion of domain walls and molecular rearrangement within domain s. Preliminary studies on binary mixtures of octadecanol and triaconta nol suggest preferential adsorption of triacontanol. Finally, domain s tructures have been observed for monolayers of octadecanethiol, althou gh the molecular packing within the domains has not been resolved.