Mapping molecular orientation of pentacene on patterned Au surface

With a photoemission electron microscope, we investigated the orientation of pentacene films deposited on Au surface that has been patterned with self-assembled monolayers (SAMs). Organic thiols X(CH2)nSH- with X = -COOH or -CH3 and an aromatic thiol; served as alignment layers to control the orientation of pentacene molecules thermally deposited on top of the SAM. According to the PEEM images and near-edge X-ray absorption fine structure spectra, a SAM exposing a non-polar methyl group, a terphenyl group or a polar carboxyl group all induced perpendicular alignment of the pentacene moiety, in contrast with parallel alignment on a bare gold surface