Unraveling the Diffusion of Bulk Ti Interstitials in Rutile TiO2(110) by Monitoring Their Reaction with O Adatoms

The diffusion of interstitial Ti 3+ species (Ti i 3+ ) in rutile TiO 2 (110) from the bulk to the surface has been studied utilizing two experimental techniques. Electron-stimulated desorption of O + ions was employed to kinetically monitor the reaction between oxygen adatoms with Ti i 3+ species at temperatures between 360 and 400 K. Scanning tunneling microscopy was also used to measure the Ti i 3+ diffusion rate. Both methods yield a rate constant k Ti i 3+ = 5 × 10 −4 s −1 at 393 K. The activation energy as measured by the rate dependence on temperature is ∼1.0 eV.