INFLUENCE OF ACOUSTIC-WAVE EXCITATION ON CO OXIDATION OVER A PT(110) SINGLE-CRYSTAL

A unique ultra-high vacuum (UHV) compatible excitation system combined with an advanced ultra-high amplitude and frequency resolution acoust ic spectrometer has been designed and constructed to permit accurate s tudies of the fundamental mechanism by which acoustic excitation influ ences heterogeneous catalytic reactions. A clean Pt{110} thin film sin gle-crystal catalyst was excited with low-energy acoustic waves (Rayle igh waves) under high vacuum and UHV conditions to increase the reacti on rate for carbon monoxide oxidation. A remarkable six-fold increase in the chemical activity was observed. By using a new, very accurate m ethod to monitor the sample temperature using high-resolution acoustic wave resonance spectroscopy (HRAWRS), a non-thermal acoustic-wave-ind uced enhancement of the reaction rate is clearly demonstrated. The pre ssure and temperature dependences of the enhancement provide some insi ght into the mechanism by which acoustic waves enhance catalytic react ions on solid surfaces.