Scanning tunneling microscopy of mass-selected Ag clusters on titania

COLL 291

Lauren B. Aubin1, Xiao Tong1, Paul R. Kemper1, Yigal Lilach1, Andrei Kolmakov1, Horia Metiu2, Michael T. Bowers1, and Steven K. Buratto1. (1) Department of Chemistry & Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106 - 9510, (2) Department of Chemistry and Biochemistry, Department of Physics, University of California, Santa Barbara, Santa Barbara, CA 93106
The catalytic activity of metal nanoparticles on oxide supports has inspired many studies which attempt to elucidate the fundamental processes behind the unique reactivity of these systems. The particular system of interest here, Ag nanoparticles on titania, has been reported to catalyze the epoxidation of propylene. Since nanoparticle size is a critical parameter for these active catalyst systems, studies which allow the controlled deposition of particular size clusters may provide insight into the fundamental properties governing catalytic behavior. Mass-selected cluster deposition from the gas phase is reported here. Agn+ cluster ions are first created by laser ablation followed by nucleation in a high pressure argon environment. They are then mass selected using a mass spectrometer and soft-landed onto a rutile titania (110) surface. The surfaces are finally examined using scanning tunneling microscopy.