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

Personal Author(s) : Schott, Joachim H. ; Yip, Christopher M. ; Ward, Michael D.

PDF Url : ADA288936

Report Date : 08 DEC 1994

Pagination or Media Count : 34

Abstract : Two-dimensional nanoclusters of (TTF)(TCNQ) (TTF = tetrathiafulvalene, TCNQ - tetracyanoquinodimethane) 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 the 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). In contrast, the intermolecular spacings between TCNQ molecules along the molecular stacking axis in Li+TCNQ nanoclusters are substantially larger than that observed in bulk M+TCNQ(dot) salts. The large intermolecular spacing in Li+TCNQ(dot) nanoclusters is consistent with Coulomb repulsion between fully reduced p = 1 TCNQ(dot) anion sites in the Li+TCNQ(dot) nanoclusters (p = formal charge).

Descriptors :   *SURFACES, *LITHIUM, *GOLD, SCANNING ELECTRON MICROSCOPES, INTERACTIONS, TUNNELING(ELECTRONICS), ELECTRONIC SCANNERS, ORIENTATION(DIRECTION), SUBSTRATES, NUCLEATION, VAPOR PHASES, ELECTRON MICROSCOPY, SUBLIMATION, LIQUID CRYSTALS, ORGANIC COMPOUNDS, MOLECULE MOLECULE INTERACTIONS, DIFFUSION, AZIMUTH, STACKING, CRYSTAL GROWTH.

Subject Categories : Physical Chemistry
      Inorganic Chemistry
      Organic Chemistry
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE