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Accession Number:
ADA288936
Title:
Self-Assembly of Low-Dimensional Molecular Nanoclusters on Au(111) Surfaces.
Descriptive Note:
Technical rept.,
Corporate Author:
MINNESOTA UNIV MINNEAPOLIS DEPT OF CHEMICAL ENGINEERING AND MATERIALS SCIENCE
Report Date:
1994-12-08
Pagination or Media Count:
34.0
Abstract:
Two-dimensional nanoclusters of TTFTCNQ TTF tetrathiafulvalene, TCNQ - tetracyanoquinodimethane and LiTCNQ-, 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 Au111 substrate, while the clusters exhibit azimuthal orientations conforming to the threefold Au 110 directions. The nanocluster morphology and structure suggest that self-assembly of the nanoclusters is governed by specific interactions between the molecular species and the substrate and molecular diffusion along 110 troughs on the Au111 substrate surface. In the case of the TTFTCNQ 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 TTFTCNQ. In contrast, the intermolecular spacings between TCNQ molecules along the molecular stacking axis in LiTCNQ nanoclusters are substantially larger than that observed in bulk MTCNQdot salts. The large intermolecular spacing in LiTCNQdot nanoclusters is consistent with Coulomb repulsion between fully reduced p 1 TCNQdot anion sites in the LiTCNQdot nanoclusters p formal charge.
Distribution Statement:
APPROVED FOR PUBLIC RELEASE
