Infrared vibrational studies of CO adsorption on Cu/Pt(111) and CuPt(111) surfaces

Journal Article · Fri May 15 00:00:00 EDT 1992 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.462378· OSTI ID:7297686

Rodriguez, J A; Truong, C M; Goodman, D W ^[1]

---

1. Department of Chemistry, Texas A M University, College Station, Texas 77843 (United States)

Adsorption of CO on ultrathin Cu films supported on Pt(111) has been studied using infrared reflection absorption spectroscopy (IRAS). Our results indicate that the infrared intensities of adsorbed CO are not representative of the relative composition of the Cu{sub {lt}1.0}/Pt(111) surfaces. The Cu-bonded CO molecules screen CO molecules bonded to Pt, making them invisible in the infrared spectrum. The screening'' effect depends on the morphology and polarizability of the Cu overlayer. Changes in the morphology of the Cu adlayer produce large variations in the position and line shape of the Cu--CO signal in the infrared spectrum. CO molecules bonded to small Cu clusters show a higher ({similar to}40 cm{sup {minus}1}) C--O stretch frequency than CO molecules adsorbed on large Cu islands. The present results were compared with those reported in the literature for the CO/Cu/Ru(0001) and CO/Cu/Rh(100) systems. For CO adsorbed on supported monolayers of Cu, a correlation was found between the strength of the Cu--CO bond, the amount of {pi} backdonation, and the C--O stretch frequency. This correlation cannot be explained using simple models of molecular orbital theory. On the bimetallic surfaces, the C--O stretch frequency is more sensitive to the charge on the metal center to which CO is bonded, than to the electron population of the CO(2{pi}) orbitals.

• OSTI ID: 7297686
• Journal Information: Journal of Chemical Physics; (United States), Vol. 96:10; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CARBON MONOXIDE
ADSORPTION
CHEMICAL BONDS
COPPER
COPPER COMPOUNDS
INFRARED SPECTRA
MORPHOLOGY
PLATINUM
PLATINUM COMPOUNDS
POLARIZABILITY
SCREENING
SURFACES
THIN FILMS
VIBRATIONAL STATES
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
ELECTRICAL PROPERTIES
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FILMS
METALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PLATINUM METALS
SORPTION
SPECTRA
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
665300* - Interactions Between Beams & Condensed Matter- (1992-)