SFG AND STM STUDIES OF THE PT(111) CRYSTAL-FACE AT ATMOSPHERIC CO ANDOXYGEN PRESSURES - PREPARATION OF PLATINUM NANOCLUSTER ARRAYS

Studies of crystal surfaces at high pressures (ca. 1 atm) and during c atalytic reactions become possible by the application of sum frequency generation (SFG) vibrational spectroscopy and scanning tunnelling mic roscopy (STM). We present the SFG spectra of CO on Pt(lll) as a functi on of pressure and show evidence for the reversible formation of carbo nyl clusters with a CO/Pt ratio of > 1 and for an incommensurate CO la yer at high pressures. These species turn over rapidly to produce CO2 during CO oxidation. STM studies show significant reconstruction of Pt (110) in both CO and O-2, while the surface structure of the Pt(lll) c rystal face exhibits only minor changes. Platinum nanocluster arrays i n the 3-100 nm range have been produced by electron beam lithography. These cluster systems produced on different oxide supports can be used as model catalysts.