Electron–ion coincidence study for the TiO2(110) surface

Photo-stimulated desorption from the TiO2(110) surface was investigated by using electron–ion coincidence spectroscopy and synchrotron radiation. The desorption of O+ ions was observed to be coincident with the emission of photoelectrons from the O 1s, Ti 2s, Ti 2p, Ti 3s and Ti 3p levels, and their satellite peaks due to the shake-up excitation. However, no ion desorption was observed in coincidence with the O 2s or valence photoelectrons. The O+ peak intensities in the coincidence spectra are analyzed, and the result is unexpected from a simple expansion of the Knotek–Feibelman model. The shake-up excitation of O 1s levels yields O+ desorption more efficiently than does the O 1s single-electron excitation.