IRAS STUDY OF CO ADSORPTION ON S-MODIFIED MO(110) SURFACES

Infrared reflection absorption spectroscopy (IRAS) was used to study t he adsorption of CO on a S-modified Mo(110) surface. As the surface S coverage is increased to 0.5 ML, the sulfur overlayer structure change s from p(2X2) to c(2X2). These changes can be observed in the IRAS spe ctra of adsorbed CO. In addition, it was noted that in the p(2X2)S ove rlayer sulfur acted mainly as a site blocker, whereas in the c(2X2)S o verlayer electron-withdrawing effects became apparent. Finally, the di ssociative adsorption of CO was seen to occur on both clean Mo(110) an d p(2X2)S/Mo(I 10) but not on c(2X2)S/Mo(I 10).