ANGLE-RESOLVED UPS STUDIES OF CO ADSORBED ON SINGLE-CRYSTAL CU - NEW INTERPRETATION OF ADSORBATE INDUCED STRUCTURES

We have studied the adsorption of CO on clean and oxygen-preadsorbed Cu(110) by means of u.v.-photoemission. A new interpretation of the adsorbate induced structures is presented. Despite the low adsorption energy of CO and Cu, we find that the 5ρ-derived level is located at a higher binding energy than it is in CO adsorbed on Ni. We suggest that the position of this level is determined by interaction with low lying electron states in Cu. Also, the 4ρ derived level is found at a higher binding energy on Cu than on Ni, as an effect of smaller extramolecular relaxation on Cu. Detailed angle resolved studies of the CO/Cu(110) system suggest that the CO molecule is adsorbed with the molecular axis at about 35° relative to the surface normal. © 1978.