Identification of defect sites on MgO(100) thin films by decoration with Pd atoms and studying CO adsorption properties.

Details

Serval ID
serval:BIB_22061
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Identification of defect sites on MgO(100) thin films by decoration with Pd atoms and studying CO adsorption properties.
Journal
Journal of the American Chemical Society
Author(s)
Abbet S., Riedo E., Brune H., Heiz U., Ferrari A.M., Giordano L., Pacchioni G.
ISSN
0002-7863 (Print)
ISSN-L
0002-7863
Publication state
Published
Issued date
2001
Volume
123
Number
25
Pages
6172-6178
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Abstract
CO adsorption on Pd atoms deposited on MgO(100) thin films has been studied by means of thermal desorption (TDS) and Fourier transform infrared (FTIR) spectroscopies. CO desorbs from the adsorbed Pd atoms at a temperature of about 250 K, which corresponds to a binding energy, E(b), of about 0.7 +/- 0.1 eV. FTIR spectra suggest that at saturation two different sites for CO adsorption exist on a single Pd atom. The vibrational frequency of the most stable, singly adsorbed CO molecule is 2055 cm(-)(1). Density functional cluster model calculations have been used to model possible defect sites at the MgO surface where the Pd atoms are likely to be adsorbed. CO/Pd complexes located at regular or low-coordinated O anions of the surface exhibit considerably stronger binding energies, E(b) = 2-2.5 eV, and larger vibrational shifts than were observed in the experiment. CO/Pd complexes located at oxygen vacancies (F or F(+) centers) are characterized by much smaller binding energies, E(b) = 0.5 +/- 0.2 or 0.7 +/- 0.2 eV, which are in agreement with the experimental value. CO/Pd complexes located at the paramagnetic F(+) centers show vibrational frequencies in closest agreement with the experimental data. These comparisons therefore suggest that the Pd atoms are mainly adsorbed at oxygen vacancies.
Pubmed
Create date
19/11/2007 9:45
Last modification date
20/08/2019 12:58
Usage data