AVS 46th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS-WeP

Paper SS-WeP29
Molecular-scale Origins of the Surface Memory Effect at a Liquid Crystal - Solid Interface

Wednesday, October 27, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: D.M. Scott, Western Washington University
Authors: D.M. Scott, Western Washington University
A.J. Brackley, Western Washington University
J.D. Mougous, Western Washington University
K.M. Foland, Western Washington University
D.L. Patrick, Western Washington University
Correspondent: Click to Email
The surface memory effect (SME) describes the phenomenon in which an initially isotropic surface is rendered anisotropic through contact with anisotropic medium, such as a liquid crystal (LC) fluid. At a LC - solid interface, the SME leads to imprinting of the director orientation onto the surface, which can in turn induce uniform alignment in the bulk LC fluid. The SME is important in LC - based opto-electric devices such as liquid crystal displays. We studied the SME in LC droplets on a polycrystalline graphite substrate using polarized optical and scanning tunneling microscopy (STM). A single crystalline monolayer with macroscopically uniform orientation was prepared by depositing material from the LC droplet in an external magnetic field. The system was found to retain memory of the original bulk orientation, even when the field was removed and the LC was heated beyond its isotropic transition temperature. Loss of the SME coincided with monolayer melting. Comparison of STM images with optical micrographs establish a direct link between molecular alignment in the monolayer adsorbed to the graphite substrate and bulk LC director orientation.