The effect of UV radiation (1.6 eV less than or equal to hv less than or equal to 5.6 eV) on the rutile surface was studied in ultrahigh vacuum (UHV) using the scanning tunneling microscope (STM). It was found that the TiO2(110)-(1 x 1) surface remains unaffected by UV irradiation. However, line defects along the (0 0 1) direction were formed on the TiO2 (I I 0)-(l x 2) surface, the cross-section for the defect formation being 10(-23.5+/-0.2) cm(2) photon(-1) (hv greater than or equal to 3.0 eV). The defects are attributed to collective oxygen removal by UV light. It was also found that the defects were stable in UHV (up to 48 h), and their formation was not temperature dependent. (C) 2003 Elsevier Science B.V. All rights reserved.