Self-Assembly of Low-Dimensional Conductors on Au(111) Surfaces.

摘要

Two-dimensional nanoclusters of (TTF) (TCNQ) (TTF = tetrathiafulvalene TCNQ = tetracyanoquinodmethane) and Li+ TCNQ-, formed on Au (111) surfaces by vapor phase sublimation under ambient conditions prior to growth of bulk crystals of these low-dimensional organic conductors, have been observed with scanning tunneling microscopy (STM) and scanning electron microscopy (SEM). The molecular planes of the constituents in individual nanoclusters are oriented perpendicular to the Au (111) substrate, while the clusters exhibit azimuthal orientations conforming to the threefold Au <110> directions. The nanocluster morphology and structure suggest that self-assembly of nanoclusters is governed by specific interactions between the molecular species and the substrate and molecular diffusion along <110> troughs on the Au (111) substrate surface. In the case of the (TTF) (TCNQ) nanoclusters, TTF and TCNQ molecules assemble into molecular rows normal to the stacking direction, with intermolecular distances along the stacking direction which are nearly identical to those observed in bulk (TTF) (TCNQ).