SURFACE STRESS EFFECTS IN CHEMICAL ACTIVATION

The adsorption of CO on Cu covered Pd (110) has been studied using ref lection absorption infrared spectroscopy and scanning tunneling micros ropy. In the submonolayer Cu coverage range the presence of Cu islands induces on uncovered Pd (110) terraces a CO configuration change. Thi s intriguing effect is not localized at Cu island boundaries (steps) b ut is of mesoscopic character penetrating up to 40 angstrom onto uncov ered Pd terraces. Potential origins of the substrate modification are discussed. Most likely the mesoscopic CO configuration change is cause d by the buildup of stress in the Pd substrate due to the substantiall y strained Cu islands.