Spectroscopy and Structure of Diamondoid-Fullerene Hybrid Molecules at the Single-Molecule Level

Diamondoids---a nanometer-scale form of carbon sharing the \textit{sp}$^{3}$ bonding structure of bulk diamond---are promising new electronic and mechanical device elements and have recently become accessible to experiments. While new fields of research have also sprouted from carbon's \textit{sp}$^{2}$ forms (such as graphene, fullerenes, and carbon nanotubes), materials representing the intersection of \textit{sp}$^{2}$ and \textit{sp}$^{3}$ bonding structures are an exciting new arena for nanoscale science and technology. In this study, we investigate hybrid molecules fusing \textit{sp}$^{2}$ and \textit{sp}$^{3}$ allotropes of carbon (in the form of C$_{60}$ fullerenes and molecular diamondoids, respectively) into one well-defined system. We use low-temperature scanning tunneling microscopy to characterize monolayers and single molecules with sub-molecular resolution. We show the degree to which the electronic properties of the hybrid molecules differ from their single-allotrope components, and highlight the intriguing electronic features that emerge which have no analog in either of the separate molecular constituents.