Amine Functionalization of Gold Surfaces: Ultra High Vacuum Deposition of Cysteamine on Au(111)

The in situ formation of prototypes of complex hybrid organic structures gives the opportunity to characterize
their morphologic and spectroscopic properties, a mandatory step toward the development of more reliable
and efficient organic devices. In this context, a proper functionalization of the substrate's surface is required
for the linkage of small molecules or proteins. We report here how thin films of cysteamine have been
successfully assembled on Au(111) by evaporation in ultra high vacuum conditions. The molecular orientation
has been investigated by means of X-ray absorption spectroscopy. Both monolayer and multilayered films of
cysteamine have been characterized by means of high-resolution photoemission spectroscopy. A compact,
homogeneous self-assembled monolayer has been obtained, which provides the functionalization of the surface
with a -NH2 linker. The investigation on the multilayer film revealed the presence of a zwitterionic cysteamine
moiety.