AN EELS STUDY OF CU ADSORBED ON O/W(110) AND CO/W(110)

The vibrational properties of 1 monolayer of Cu adsorbed on O/W(110), Cu1/O/W(110), O/Cu1/W(110) and Cu1-1.5/CO/W(110) were studied at 90 K and on heating to see if the existence of sandwich structures and the electric shielding by single metal layers suggested by previous work [N. Shamir, J.C. Lin and R. Gomer, J. Chem. Phys. 90 (1989) 5135] could be confirmed. It was found that a monolayer of Cu screens the O-W dipole moment effectively while 1.5 Cu monolayers were required for CO on W, probably because in that case a continuous Cu layer is not formed. It was also found that heating Cu1/O/W(110) and O/Cu1W(110) layers gave results which support previous findings on O-Cu segregation [J.S. Lin, N. Shamir and R. Gomer, Surf. Sci. 206 (1988) 206].