AVS 49th International Symposium
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP28
New Insights into Self-Assembled Monolayer Structure and Dynamics

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Surface Science Poster Session
Presenter: S.B. Darling, The James Franck Institute at The University of Chicago
Authors: S.B. Darling, The James Franck Institute at The University of Chicago
S.J. Sibener, The James Franck Institute at The University of Chicago
Correspondent: Click to Email
We have studied the effect of adsorption of a low-density alkanethiol monolayer on the state of the Au(111) reconstruction. It is commonly believed that the substrate deconstructs following formation of a thiolate self-assembled monolayer, but our results suggest this is not always the case. Helium diffraction from 1-decanethiol (C10) and 1-octanethiol striped phase monolayers is exploited to establish the surface nearest-neighbor spacing and to illustrate a unit cell corresponding to the long dimension of the (23x@sr@3) reconstruction. Complementary scanning tunneling microscopy data are also presented that show persistence of the reconstruction during growth of a decanethiol striped phase monolayer and no evidence for vacancy islands typically associated with deconstruction. Our model involving a still-reconstructed substrate is consistent with all of the available data. Furthermore, the low-energy surface vibrational structure of the (11.5x@sr@3) striped phase of C10 has also been studied. Energy-transfer spectra for this system exhibit a dispersionless inelastic feature at 8 meV. We assign this to the frustrated translation of the entire molecule vibrating with polarization perpendicular to the surface. These results further the understanding of the forces that govern nanoscale self organization.