Snapshots of Crystal Growth: Nanoclusters of Organic Conductors on Au(111) Surfaces
Abstract
Mono- and multilayer crystalline nanoclusters of tetra-hiafulvalene- tetracyanoquinodimethane ((TTF) (TCNO)), a low-dimensional organic conductor in the bulk form, can be formed readily on Au(111) surfaces by vapor phase sublimation under ambient conditions. Scanning tunneling microscopy of monolayer (TTF)(TCNQ) films reveals a two-dimensional density of states (DOS) that is consistent with the arrangement of TTF and TCNO molecules in the ac face of bulk (TTF)(TCNO), in which the molecular planes are nearly parallel to the Au(111) substrate. In contrast, clusters with thicknesses corresponding to two or three molecular layers exhibit a transformation to a highly anisotropic DOS that can be attributed to interlayer molecular overlap in segregated TTF and TCNQ molecular chains along the c-axis, which can be described as 'molecular wires'. The orientation of the crystalline (TTF)(TCNO) clusters is preserved throughout the crystal growth sequence, leading to meso- and macroscopic (TTF)(TCNO) needles that are oriented perpendicular to the Au(111) substrate. These studies provide visualization of crystal growth from the initial stages of nucleation to macroscopic crystals, and a Organic Conductors, Atomic Force Microscopy, Nucleation, Fractals.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 20, 1994
- Accession Number
- ADA280976
Entities
People
- Joachim H. Schott
- Michael D. Ward
Organizations
- University of Minnesota