Abstract Flat and highly (111) oriented gold and silver films were prepared by physical vapour deposition (PVD) using optimized deposition parameters. On these films, which were characterized with atomic force microscopy (AFM), scanning tunneling microscopy (STM), X-ray dif- fraction (XRD) and X-ray photoelectron spectroscopy (XPS), titanium dioxide films were deposited by electron beam evaporation and dip coating. Dip coating from tita- nium tetraisopropoxide solutions resulted in films with different morphology and coverage depending on the alkoxide concentration (0.009 mol/L – 0.60 mol/L) and the post-treatment. Scanning electron microscopy (SEM) and AFM revealed that the deposited TiO 2 consists of amorphous, highly porous islands when the applied alkoxide concentration is high (0.05 mol/L – 0.6 mol/L). At higher temperatures these amorphous TiO 2 islands sin- tered significantly and crystallized to anatase. In contrast, transparent TiO 2 films were obtained from low concen- trated alkoxide solutions (< 0.01 mol/L) which covered the whole substrate, similar to electron beam evaporated thin films. Sputter profiles with ion scattering spectro- scopy (ISS) indicated that the film thickness is in the range of 2 nm when alkoxide solutions with a concentration of 9 mmol/L are used. The deposition of TiO 2 by electron beam evaporation normally resulted in significantly re- duced TiO 2 films, completely oxidized ones were ob- tained when deposition was performed at elevated oxygen partial pressures (p(O 2 ) > 2 × 10 –5 mbar). Introduction Noble metals dispersed on metal oxide supports often ex- hibit a modified catalytic activity [1, 2] compared with the pure metal. For example, Au on TiO 2 or ZrO 2 catalyzes CO-oxidation at low temperatures [3, 4], whereas the gold or the oxide itself are inactive under these conditions. To study the influence of the interface on the reaction, thin and flat metal oxide films (TiO 2 , ZrO 2 ) on highly conduc- tive single crystalline supports (gold, silver) are promis- ing model systems. Thin gold and silver films can be epi- taxially grown on mica [5, 6] and a variety of techniques are available for the deposition of thin TiO 2 films includ- ing physical vapour deposition [7, 8], chemical vapour de- position [9] and sol-gel methods [10, 11]. However, only a few data regarding the use of single crystalline gold or silver supports and the surface spectroscopic analysis of metal oxide films on these substrates are available in liter- ature. Hence, here is reported on the preparation and char- acterization of epitaxially grown gold and silver films on mica as substrate for the deposition of TiO 2 films. Two different coating techniques were used for metal oxide de- position: electron beam evaporation of TiO 2 and dip coat- ing from titanium alkoxide solutions. Experimental Gold and silver films (99.999%, Cendres & Métaux) were evapo- rated by resistive heating from a tungsten boat onto air cleaved ruby muscovite mica (Provac AG) in a Bal-Tec BAE 370 vacuum coating system with integrated quartz crystal deposition controller Inficon XTC/2 from Leybold (Switzerland). Further details are given in a previous paper [6]. On these films titanium and zirconium oxide were deposited by reactive electron beam evaporation (TFI Telemark, model 279) of the corresponding oxide from a graphite crucible. Evaporation dur- ing different oxygen partial pressures (p(O 2 ) = 4 × 10 –7 mbar – 4 × 10 –5 mbar) and at different substrate temperatures (T S = 300 K – 620 K, heating from the backside of the sample) was performed. Some of the films were post-treated ex situ in a quartz reactor. The alternative deposition of the titanium dioxide films was performed typically by the following procedure: Titanium tetraisopropoxide was added under argon stream to isopropanol (dried over molecu- lar sieves, all reagents chemical grade) and held under argon. From differently concentrated solutions (0.009 mol/L – 0.6 mol/L) the samples were prepared by dip coating in Ar atmosphere and dried in air followed by post-treatment in oxygen at different tempera- tures in a quartz reactor. The films were analyzed with different methods using the fol- lowing equipment: X-ray diffraction patterns, recorded on a Siemens J.-D. Grunwaldt · U. Göbel · A. Baiker Preparation and characterization of thin TiO 2 -films on gold/mica Fresenius J Anal Chem (1997) 358 : 96–100 © Springer-Verlag 1997 Received: 24 June 1996 / Revised: 4 December 1996 / Accepted: 13 December 1996 ORIGINAL PAPER J.-D. Grunwaldt · U. Göbel · A. Baiker () Department of Chemical Engineering and Industrial Chemistry, Swiss Federal Institute of Technology, ETH-Zentrum, CH-8092 Zürich, Switzerland