STM study of charge transfer and the role of rest-atoms in the binding of benzene to Si(1 1 1)7 × 7

Chemisorbed benzene was studied by room temperature STM at low coverage on Si(1 1 1)7 × 7. Images taken of both filled and unfilled states show effects on adatoms near the benzene molecules. Filled states imaging shows a significant amount of what we believe to be charge transfer throughout the involved half unit cell. For a benzene molecule bound to a middle adatom there is also significant charge transferred from the adjacent middle adatom of the neighbouring half unit cell. Symmetry considerations allow for the conclusion that benzene binds in a di-σ bridge configuration between an atom and rest-atom. Evidence has been obtained that charge transfers away from the involved rest-atom to adjacent adatoms. Empty states imaging of the π∗ state also provides evidence for the involvement of a rest-atom in the binding.