Defects and Pd growth on the reduced SnO2(1Â 0Â 0) surface

Scanning tunneling microscopy experiments on a clean, reduced SnO2(1 0 0)-(1 × 1) surface reveal surface defects with zero-, one-, and two-dimensions. Point defects consist of missing SnO/SnO2 units. Line defects are probably crystallographic shear planes that extend to the surface and manifest themselves as rows of atoms, shifted half a unit cell along the [0 1 0] direction. Their ends act as preferential nucleation sites for the formation of Pd clusters upon vapor deposition. Areas of a more reduced surface phase, still with a (1 × 1) structure and a half-unit cell deep, form at [0 0 1]-oriented step edges.