title: Visualization and manipulation of individual dopant states in single conjugated oligomers.
abstract: Nonlinear excitations associated with dopant states play fundamental roles for charge transport in conjugated polymers. Here we report on real-space visualization of individual dopant states in single conjugated oligomers of poly-para-phenylene using cryogenic scanning tunneling microscopy and spectroscopy. We have found that these states exhibit a typical spatial extension of 4 nm along the oligomers. In particular, these states create a shallow level inside the band gap of the parent oligomers. The origin of these states is traced to a novel doping mechanism of dehydrogenation of the phenylene moiety. Furthermore, we use a scanning tunneling microscope tip to charge/discharge the dopant states and measure their lifetimes. The present results demonstrate a strategy to characterize and manipulate individual dopant states in conjugated polymers with subnanometer resolution.
authors.affiliation: Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China.
authors.forename: Shiyong
authors.initials: S
authors.lastname: Wang
authors.forename: Weihua
authors.initials: W
authors.lastname: Wang
authors.forename: Nian
authors.initials: N
authors.lastname: Lin