CO adsorption on Cu3Pt(111) and CuPt3(111): a comparative HREELS study

The adsorption of CO on the Cu3Pt(111) and the CuPt3(111) surface at 100 K has been studied using high resolution electron energy loss spectroscopy. B oth surfaces show CO adsorption on on-top platinum and copper sites. The re lative amount of copper sites populated is - as can be expected - higher on the Cu3Pt(111) surface. Additionally, bridge sites are populated on both s urfaces. Due to the different stoichiometries of the substrates the populat ion of these sites shows significant differences. The loss energies for CO on CuPt3(111) show little difference compared to C O on Pt(111). However, in contrast to Pt(111) all sites are populated concu rrently on CuPt3(111). For CO on Cu3Pt(111) a large red-shift of the on-top C-O vibrational loss has been found for platinum sites accompanied by a si gnificant weakening of the Pt-CO bond compared to CO on Pt(111). (C) 1999 E lsevier Science B.V. All rights reserved.