AVS 45th International Symposium
    Surface Science Division Monday Sessions
       Session SS2-MoM

Paper SS2-MoM8
Low Temperature STM Imaging of Furan Molecules on Pd(111)

Monday, November 2, 1998, 10:40 am, Room 309

Session: Molecular Adsorbates on Metals
Presenter: S. Chiang, University of California, Davis
Authors: C.A. Pearson, University of California, Davis
S. Chiang, University of California, Davis
A. Loui, University of California, Davis
D.N. Futaba, University of California, Davis
Correspondent: Click to Email
The cyclotrimerization reaction of acetylene to benzene is known to proceed readily in ultra high vacuum on the Pd(111) surface. Thermal desorption spectroscopy has measured furan (C@sub 4@H@sub 4@O)@footnote 1@ and thiophene (C@sub 4@H@sub 4@S)@footnote 2@ desorbing from the Pd(111) surface following the coadsorption of acetylene with oxygen and sulfur respectively. Using low temperature scanning tunneling microscopy (STM), we have imaged furan molecules adsorbed on the Pd(111) surface. Dosing and imaging of the sample was performed at 200 K. While no changes were evident with low energy electron diffraction (LEED), we observed localized ordering with the STM for monolayer coverage. Furan molecules form ordered rows in three different domains oriented 120° apart. The ordered regions are roughly 50 Å to 100 Å in size. Higher resolution images show individual molecules within the rows. Measurements of the intermolecular spacing in the images provide information about the molecular tilt on the surface. Images of individual molecules will also be compared with predicted theoretical STM images from extended Hückel molecular orbital theory. @FootnoteText@ @footnote 1@R.M. Ormerod, R.M. Lambert, Cat. Lett. 6, 121 (1990). @footnote 2@A.J. Gellman, Langmuir 7, 827 (1991).