HYDROGEN AND CO SPILLOVER AT CU/RH(100) BIMETALLIC SURFACES STUDIED BY HIGH-RESOLUTION ELECTRON ENERGY-LOSS SPECTROSCOPY

Hydrogen and CO spillover at Cu/Rh(100) interfaces has been studied using high-resolution electron energy-loss spectroscopy (HREELS). Upon hydrogen exposure to 0.33 ML of Cu on Rh(100) and subsequent annealing to 250 K, hydrogen atoms migrate from Rh to Cu as evidenced by the appearance of the HR.EELS loss feature corresponding to a H-Cu vibration at 866 cm-1. In addition, deposition of approximately 3 ML of Cu onto a H-preadsorbed Rh ( 100) surface induces the hydrogen atoms to spillover from the Rh(100) surface onto the Cu overlayers. Likewise, CO is found to diffuse from Cu sites to Rh sites as CO-covered Cu/Rh(100) surfaces are heated to approximately 250 K. Furthermore, depositing Cu onto a CO-precovered Rh(100) surface at 90 K results in spillover of CO from Rh to Cu overlayers leading to a CO/Cu/Rh(100) structure.