AVS 45th International Symposium
    Applied Surface Science Division Thursday Sessions
       Session AS-ThP

Paper AS-ThP5
Identification of Halogen Atoms in STM Images of Substituted Phenyloctadecylethers

Thursday, November 5, 1998, 5:30 pm, Room Hall A

Session: Aspects of Applied Surface Science Poster Session
Presenter: H.S. Lee, University of Texas, Dallas
Authors: H.S. Lee, University of Texas, Dallas
S. Iyengar, University of Texas, Dallas
I.H. Musselman, University of Texas, Dallas
Correspondent: Click to Email
A homologous series of para-substituted phenyloctadecylethers (X-POEs, X = H, Cl, Br and I) was prepared and characterized using @super 1@H NMR and GC/MS. Scanning tunneling microscopy (STM) images acquired from these ethers have revealed a bias-dependent contrast which corresponds to calculated electron density contours of various X-POE molecular orbitals. STM images of the X-POEs reflecting the electron density contour of the highest occupied molecular orbital (HOMO) exhibited four bright spots - one for the halogen atom, two representing the pair of lobes of the phenyl ring, and one for the oxygen/alpha-carbon atoms. For each X-POE, a minimum of three sets of four submolecular resolution HOMO images were acquired. The intensities of the spots for the halogen atom and the lobe of the phenyl ring closest to the halogen were measured and their ratio was calculated. The ratios for Cl-POE, Br-POE and I-POE were 0.48 ± 0.05, 0.58 ± 0.05 and 0.75 ± 0.07, respectively. An analysis of variance revealed that the intensity ratios of the X-POEs could be clearly distinguished among all data sets.@footnote 1@ @FootnoteText@ @footnote 1@ The support of this research by a grant from the Robert A. Welch Foundation is gratefully acknowledged.