Accession Number : ADA306862

Title :   Electrochemical Annealing and Friction Anisotropy of Domains in Epitaxial Molecular Films.

Descriptive Note : Technical rept. 1 May-30 Jun 96,

Corporate Author : MINNESOTA UNIV MINNEAPOLIS DEPT OF CHEMICAL ENGINEERING AND MATERIALS SCIENCE

Personal Author(s) : Last, Julie A. ; Ward, Michael D.

PDF Url : ADA306862

Report Date : 08 APR 1996

Pagination or Media Count : 18

Abstract : Electrochemical annealing of domain boundary defects in an epitaxial monolayer whose structure mimics the (001) layers of the organic superconductor Beta-bis(ethylenedithio)tetrathiafulvalene trioxide, (ET)2I3, has been visualized in situ using real-time atomic force microscopy. These defects are observed readily by lateral force imaging and high resolution contact mode imaging reveals that the domains are oriented at angles of +/-n6O because of epitaxy with the HOPG substrate. The frictional contrast between domains is due to the anisotropy molecular field encountered by the tip and is a direct consequence of the crystalline order of the rigid monolayer. Potential cycling about the deposition potential resulted in a reduction in the number of domains, with the smaller domains eventually adopting the orientation of surrounding larger ones, ultimately forming large (>15 micrometer(s) squared) defect free monolayers. This demonstrates that the defect density of redox-active molecular films can be reduced by relatively simple means.

Descriptors :   *ANNEALING, *MOLECULES, *ELECTROCHEMISTRY, *EPITAXIAL GROWTH, *DEFECTS(MATERIALS), *FRICTION, DENSITY, LAYERS, SUPERCONDUCTORS, SUBSTRATES, CRYSTALS, CYCLES, BOUNDARIES, DEPOSITION, OXIDES, ANISOTROPY, ORGANIC COMPOUNDS, RIGIDITY, OXIDATION REDUCTION REACTIONS, MONOMOLECULAR FILMS.

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

Distribution Statement : APPROVED FOR PUBLIC RELEASE