Adsorption of diferrocenylacetylene on Au(111) studied by scanning tunneling microscopy

Rebecca C. Quardokus, Natalie A. Wasio, Ryan P. Forrest, Craig S. Lent, Steven A. Corcelli, John A. Christie, Kenneth W. Henderson, S. Alex Kandel
2013 Physical Chemistry, Chemical Physics - PCCP  
Scanning tunneling microscopy images of diferrocenylacetylene (DFA) coadsorbed with benzene on Au(111) show individual and close-packed DFA molecules, either adsorbed alongside benzene or on top of a benzene monolayer. Images acquired over a range of positive and negative tip-sample bias voltages show a shift in contrast, with the acetylene linker appearing brighter than the ferrocenes at positive sample bias (where unoccupied states primarily contribute) and the reverse contrast at negative
more » ... s. Density functional theory was used to calculate the electronic structure of the gas-phase DFA molecule, and simulated images produced through two-dimensional projections of these calculations approximate the experimental images. The symmetry of both experimental and calculated molecular features for DFA rules out a cis adsorption geometry, and comparison of experiment to simulation indicates torsion around the inter-ferrocene axis between 901 and 1801 (trans); the cyclopentadienyl rings are thus angled with respect to the surface.
doi:10.1039/c3cp50225b pmid:23552908 fatcat:7nkvqyjw2ncg3ecjz45u7arlla