Regensburg 2000 – wissenschaftliches Programm

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O: Oberflächenphysik

O 11: Postersession (Eröffnung)

O 11.34: Poster

Montag, 27. März 2000, 19:00–22:00, Bereich C

Water adsorption on TiO₂: Investigations with MIES, UPS and TPD — •Stefan Krischok^1,2, Jens Günster^1,3, Jeffrey Stultz¹ und D. Wayne Goodman¹ — ¹Department of Chemistry Texas A& M University, College Station, Texas, 77843-3255, USA — ²permanent address: Physikalisches Institut, TU Clausthal, Leibnizstraße 4, 38678 Clausthal-Zellerfeld, Germany — ³permanent address: Institut für Nichtmetallische Werkstoffe, TU Clausthal, Zehntnerstraße 2A, 38678 Clausthal-Zellerfeld, Germany

TiO₂ films grown on a Mo(100) substrate were exposed to water while metastable impact electron (MIES) and UPS(HeI) spectra were collected in situ. An unambiguous identification of the spectral features from OH and H₂O species was possible by MIES. Additionally, TPD experiments were carried out in order to get information about desorption temperature and saturation coverage for different temperatures. MIES gives a good insight in the early stage of water adsorption. Due to its high surface sensitivity only the outermost layer is investigated [1]. For very low coverages at room temperature water adsorbs dissociatively. At lower temperatures and larger coverages water adsorbs molecularly. The results are compared with available studies on TiO₂ single crystals (UPS, TPS, XPS, HREELS).

[1] Y. Harada, S. Masuda and H. Ozaki, Chemical Reviews, Vol.97, 1997