The adsorption and surface diffusion of CO on Pd/W( 110) and Cu/Rh( 100) surfaces have been studied using infrared reflection-absorption spectroscopy (IRA.?). For CO adsorbed on 0.14 ML Pd on W ( I lo), the CO is found to diffuse from Pd to W at approximately 200 K. Likewise, CO adsorbed on ~0.1 ML Cu on Rh( 100) will diffuse from the Cu to the Rh at approximately 250 K. In addition, the CO ads...