AVS 60th International Symposium and Exhibition
    Scanning Probe Microscopy Focus Topic Thursday Sessions
       Session SP+AS+BI+EM+MI+NS+SE+SS-ThA

Paper SP+AS+BI+EM+MI+NS+SE+SS-ThA12
Mapping Local Dipole Domains within Two-Dimensional Plastic Lattices

Thursday, October 31, 2013, 5:40 pm, Room 202 C

Session: Probe-sample Interactions, Nano-manipulation and Emerging Instrument Formats
Presenter: J.C. Thomas, University of California at Los Angeles
Authors: J.C. Thomas, University of California at Los Angeles
J.J. Schwartz, University of California at Los Angeles
H.S. Auluck, University of California at Los Angeles
G. Tran, University of California at Los Angeles
J. Gilles, University of California at Los Angeles
S. Osher, University of California at Los Angeles
C.A. Mirkin, Northwestern University
P.S. Weiss, University of California at Los Angeles
Correspondent: Click to Email
We have observed aligned dipoles forming two-dimensional plastic lattices in self-assembled monolayers of carboranethiols on Au{111}. We have used scanning tunneling microscopy (STM) and simultaneously acquired local barrier height images of 9,12-dicarba-closo-dodecaborane o-9-carboranethiol (O9) monolayers on Au{111} at 4K in extreme high vacuum to determine the local structures and dipole orientations within the monolayers. The molecular structure of O9 is that of a symmetric cage; a two-dimensional plastic lattice of aligned dipoles is formed through favorable intermolecular dipole-dipole interactions after chemisorption. Local barrier height images juxtaposed with the simultaneously recorded topography reveal directional dipole offsets within domains. New imaging analysis methods were used to overlay the multimodal data and determine molecular dipole orientations. We employ Monte Carlo simulations to model the dipole-dipole interactions, and to predict alignment at low temperature. We compare and contrast topographic and simultaneously acquired local barrier height images of 1,7-dicarba-closo-dodecaborane m-1-carboranethiol (M9) on Au{[111} in which the largest dipole is due to the sulfur-gold bond (as opposed to the cage) and is aligned to topographic maxima in STM images.