IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Wednesday Sessions
       Session SS2-WeM

Paper SS2-WeM10
Experimental and Theoretical Imaging of the Decomposition of Furan on Pd(111)

Wednesday, October 31, 2001, 11:20 am, Room 121

Session: Surface Reactions on Metals
Presenter: A. Loui, University of California, Davis
Authors: A. Loui, University of California, Davis
D.N. Futaba, Hokkaido University, Japan
S. Chiang, University of California, Davis
Correspondent: Click to Email
Experimental and theoretical studies have been performed on the decomposition of furan, C@sub4@H@sub4@O, adsorbed on Pd(111). The reaction of furan on this substrate has been previously studied using LITD/FTMS.@footnote 1@ In that study, furan was observed to decompose to H, CO, and C@sub3@H@sub3@ in the temperature range of 280-320 K; the latter species can then dimerize to form benzene above 350 K. Using scanning tunneling microscopy, our observations of the pre-reaction surface at 126 K show features adsorbed along the upper step edges, which match theoretical images of furan@footnote 2@ (generated using Extended Hückel Theory) in overall shape, size and internal structure. Comparison of the calculated and experimental furan features show that these molecules seem to preferentially orient with the oxygen atom facing away from or towards the step edge. Data obtained in the temperature range of 280-320 K show evidence of decomposition, which is consistent with the previous desorption studies. We have observed two distinct types of features that are discernible based on size, location and internal detail. The larger features populate the upper step edge region and are consistent with the data obtained at 126 K for unreacted furan. The smaller features appear to be clumped along the lower step edges. Based on the size and the known reaction products, we attribute these features to C@sub3@H@sub3@. In some reaction data, this species is resolved as an oblong feature with a bisecting node, agreeing well with the calculated images for flat-lying C@sub3@H@sub3@ molecules in shape, size and internal structure. These experiments indicate that there is a fundamental difference in the properties of the upper step edge versus the terrace with respect to this decomposition reaction. @FootnoteText@ @footnote 1@ Caldwell, T. E. and Land, D. P., Polyhedron, 16(18), 3197 (1997). @footnote 2@ Futaba, D. N. and Chiang, S., J. Vac. Sci. Technol. A, 15(3), 1295 (1997).