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Atomic force microscopy AFM investigations of polyamidoamine PAMAM Starburst Trademark dendrimers, generations 4 and 8 G4, G8, absorbed on Au 111 surfaces were conducted. By controlling dendrimer concentration and exposure time during adsorption, coverages ranging from completely isolated molecules to a monolayer were prepared. The individual dendrimer molecules forming a monolayer were clearly imaged. Upon exposure to hexadecanethiol, the shapes of individual dendrimers change and they become taller and narrower as more stable thiol-Au bonds replace some of the amine-Au bonds. In the case of monolayers, exposure to hexadecanethiol causes the dendrimers to gradually agglomerate, forming dendrimer pillars up to 30 nm in height and freeing progressively more surface area for thiol adsorption.

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