NEW MODEL CATALYSTS - UNIFORM PLATINUM CLUSTER ARRAYS PRODUCED BY ELECTRON-BEAM LITHOGRAPHY

Platinum particles of 50 nm diameter and 15 MI height at 200 nm spacin g have been prepared on an oxidized silicon wafer using electron beam lithography. These particles were cleaned of surface carbon with low e nergy (400 eV) neon ion sputtering. The rate of ethylene hydrogenation over this new model catalyst was measured in a UHV chamber equipped w ith a high pressure cell for catalytic reaction. Measured turnover num bers are on good agreement with previous work. Atomic force microscopy (AFM) and temperature programmed desorption (TPD) indicate the sample structure remains unaltered by the cleaning and the catalytic reactio n.