title: Charging effects on bonding and catalyzed oxidation of CO on Au8 clusters on MgO.
abstract: Gold octamers (Au8) bound to oxygen-vacancy F-center defects on Mg(001) are the smallest clusters to catalyze the low-temperature oxidation of CO to CO2, whereas clusters deposited on close-to-perfect magnesia surfaces remain chemically inert. Charging of the supported clusters plays a key role in promoting their chemical activity. Infrared measurements of the stretch vibration of CO adsorbed on mass-selected gold octamers soft-landed on MgO(001) with coadsorbed O2 show a red shift on an F-center-rich surface with respect to the perfect surface. The experiments agree with quantum ab initio calculations that predict that a red shift of the C-O vibration should arise via electron back-donation to the CO antibonding orbital.
authors.affiliation: School of Physics, Georgia Institute of Technology, Atlanta, GA 30332-0430, USA.
authors.forename: Bokwon
authors.initials: B
authors.lastname: Yoon
authors.forename: Hannu
authors.initials: H
authors.lastname: Häkkinen
authors.forename: Uzi
authors.initials: U
authors.lastname: Landman
authors.forename: Anke S
authors.initials: AS
authors.lastname: Wörz
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Antonietti
authors.forename: Stéphane
authors.initials: S
authors.lastname: Abbet
authors.forename: Ken
authors.initials: K
authors.lastname: Judai
authors.forename: Ueli
authors.initials: U
authors.lastname: Heiz