DIFFUSION OF THE SILICON DIMER ON SI(001) - NEW POSSIBILITIES AT 450 K

We report on the discovery of a novel diffusion pathway for silicon di mers on the Si(001) surface. As a small molecule, the dimer's configur ation can play a central role in its diffusion. Using scanning tunneli ng microscopy movies at temperatures near 450 K, we show, in real time , changes in the dimer's configuration during its diffusion. These cha nges in configuration provide a pathway for diffusion across the subst rate dimer rows, unlike the well-known diffusion along the dimer rows. The important energies involved in dimer row crossing are measured.