AVS 47th International Symposium
    Surface Science Thursday Sessions
       Session SS1+MC-ThA

Paper SS1+MC-ThA8
Direct Observation of Native Hydrogen Adatoms on Rutile TiO@sub 2@(110) Surface

Thursday, October 5, 2000, 4:20 pm, Room 208

Session: Oxidation and Molecule-Oxide Interactions
Presenter: T. Fujino, Osaka University, Japan
Authors: T. Fujino, Osaka University, Japan
K. Inudzuka, Osaka University, Japan
T. Okuno, Osaka University, Japan
M. Katayama, Osaka University, Japan
K. Oura, Osaka University, Japan
Correspondent: Click to Email
Titanium dioxide (TiO@sub 2@) surface has received considerable attention because TiO@sub 2@ is the material of photocatalyst such as the photodecomposition of water. Over the past few years a considerable number of studies have been made on the analysis of rutile TiO@sub 2@(110) surface composition and structure. Most of these studies were conducted using microscopic techniques such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM). However, the information of hydrogen atoms adsorbed on TiO@sub 2@(110) surface seems to be lacking because it is difficult to detect the surface hydrogen using STM or AFM. In the present study, we have investigated the structure and composition of the rutile TiO@sub 2@(110) using coaxial impact collision ion scattering spectroscopy (CAICISS), time-of-flight elastic recoil detection analysis (TOF-ERDA) and low energy electron diffraction (LEED). CAICISS and TOF-ERDA have been proved to be useful techniques for in situ observation of surface structure and composition, in particular, for the determination of the amount of surface hydrogen atoms. When the sample was introduced into ultra high vacuum (UHV) chamber without any treatments, a large quantity of hydrogen and oxygen atoms adsorb on the surface. These atoms can be attributed to water molecules. After annealing the sample at 800°C in UHV, the clean surface of TiO@sub 2@(110) with the LEED pattern of a sharp 1x1 spots was obtained. It was found from the CAICISS measurement that this surface formed bulk terminated structure, known as bridging oxygen rows model. However, it was also found from the TOF-ERDA measurement that the hydrogen atoms still resided on the surface. These hydrogen atoms are not components of water molecules but directly chemisorb on the TiO@sub 2@(110)1x1 surface. Thus, native hydrogen adatoms on the TiO@sub 2@ surface was directly observed and evidenced. Detailed results will be discussed in the presentation.