and surface reactions in ceria reduction and oxidation.

No abstract

We report on scanning tunneling microscopy (STM) studies performed with single crystalline W[001] tips on a graphite(0001) surface. Results of distance-dependent STM experiments with sub-ångström lateral resolution and density functional theory electronic structure calculations show how to controllably select one of the tip electron orbitals for highresolution STM imaging. This is confirmed by experimental images reproducing the shape of the 5dxz,yz and 5d x 2 −y 2 tungsten atomic orbitals. The presented data demonstrate that the application of oriented single crystalline probes can provide further control of spatial resolution and expand the capabilities of STM.