Reactions of mixed silver-gold cluster cations Ag{sub m}Au{sub n}{sup +} (m+n=4,5,6) with CO: Radiative association kinetics and density functional theory computations
- Institut fuer Nanotechnologie, Forschungszentrum Karlsruhe, D-76021 Karlsruhe (Germany)
Near thermal energy reactive collisions of small mixed metal cluster cations Ag{sub m}Au{sub n}{sup +} (m+n=4, 5, and 6) with carbon monoxide have been studied in the room temperature Penning trap of a Fourier transform ion-cyclotron-resonance mass spectrometer as a function of cluster size and composition. The tetrameric species AgAu{sub 3}{sup +} and Ag{sub 2}Au{sub 2}{sup +} are found to react dissociatively by way of Au or Ag atom loss, respectively, to form the cluster carbonyl AgAu{sub 2}CO{sup +}. In contrast, measurements on a selection of pentamers and hexamers show that CO is added with absolute rate constants that decrease with increasing silver content. Experimentally determined absolute rate constants for CO adsorption were analyzed using the radiative association kinetics model to obtain cluster cation-CO binding energies ranging from 0.77 to 1.09 eV. High-level ab initio density functional theory (DFT) computations identifying the lowest-energy cluster isomers and the respective CO adsorption energies are in good agreement with the experimental findings clearly showing that CO binds in a ''head-on'' fashion to a gold atom in the mixed clusters. DFT exploration of reaction pathways in the case of Ag{sub 2}Au{sub 2}{sup +} suggests that exoergicities are high enough to access the minimum energy products for all reactive clusters probed.
- OSTI ID:
- 20864291
- Journal Information:
- Journal of Chemical Physics, Vol. 125, Issue 10; Other Information: DOI: 10.1063/1.2348876; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ADSORPTION
ATOMIC CLUSTERS
BINDING ENERGY
CARBON MONOXIDE
CATIONS
COLLISIONS
DENSITY FUNCTIONAL METHOD
EV RANGE 01-10
FOURIER TRANSFORMATION
GOLD
ION CYCLOTRON-RESONANCE
ISOMERS
MASS SPECTROMETERS
MOLECULAR STRUCTURE
REACTION KINETICS
SILVER
TEMPERATURE RANGE 0273-0400 K