Acetone Chemistry On Oxidized Rutile TiO2(110)

Surface defects are known to dominate both the electronic and chemical properties of metal oxide surfaces, an object of much study for use in catalytic processes. In order to study surface chemistry in detail, an ultra-high vacuum (UHV) chamber was designed to combine a LEED and STM system. Construction is underway, with a reported initial base pressure of 10−9 Torr revealing no major leaks. On a fully functioning system, we studied the relationship between acetone and oxygen adatoms on rutile TiO2(110) using scanning tunneling microscopy (STM). We report an acetoneassisted oxygen adatom diffusion mechanism. The STM images from the same area reveal that acetone molecules preferentially adsorb to oxygen vacancy sites at room temperature. Sequences of isothermal STM images directly show that diffusion of acetone over oxygen adatom sites causes apparent motion of the adatoms. We propose a mechanism whereby the acetone diffuses along the Ti5c row and exchanges oxygen with the adatom, creating an apparent motion of the defect.