ESDIAD studies of the structure of TiO 2(110)(1 × 1) and (1 × 2) surfaces and interfaces in conjunction with LEED and STM

Abstract

The TiO 2(110)-(1 × 1) surface and its reconstruction as a (1 × 2) form have been studied with low energy electron diffraction (LEED), electron stimulated desorption ion angular distribution (ESDIAD) and scanning tunnelling microscopy (STM). Oxygen ion desorption occurs within a lobe perpendicular to the (1 × 1) surface, changing to two off-normal lobes for the (1 × 2) reconstruction. This transformation in the ESDIAD pattern is consistent with the added Ti 2O 3 row model of the (1 × 2) reconstruction proposed by Onishi and Iwasawa. STM studies of the stoichiometric and electron irradiated surfaces reinforce the association of the O + ESD contribution with majority sites at the surface. Adsorption of acetic acid on the (1 × 1) surface produces a (2 × 1) overlayed and induces a reconstruction of the underlying substrate. ESDIAD reveals H + ions emitted off-normally from dissociatively adsorbed acetate, and along the surface normal from surface hydroxyls. Adsorption of acetic acid on the (1 × 2) surface does not modify the LEED pattern, but ESDIAD reveals H + desorption with a weaker off-normal contribution consistent with the Ti 2O 3 model of the reconstruction.