Berlin 2014 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 2: Clusters
MO 2.5: Vortrag
Montag, 17. März 2014, 11:30–11:45, BEBEL SR144
CO binding to small transition metal alloy clusters — David Yubero Valdivielso1, Wieland Schöllkopf2, and •André Fielicke1 — 1Institut für Optik und Atomare Physik, Technische Universität Berlin, Germany — 2Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
We report on first experiments performed with the new infrared Free Electron Laser at the Fritz-Haber Institute in Berlin. The intense and widely tunable (so far 400–2300 cm−1) IR radiation from the FEL is used to obtain cluster size and composition selective IR spectra of CO complexes of metal alloy clusters via IR multiple photon dissociation. Investigating the binding of carbon monoxide to metal sites via vibrational spectroscopy is frequently used to characterize their electronic and structural properties. The activation of the C-O bond that is probed via the C-O stretching frequency highly depends on the nature of the metal, leading to a transition from molecular to dissociative chemisorption for the earlier transition metals. This is usually related to the rise of the d band center towards the earlier transition metals that allows for a stronger interaction with the CO’s 2π* orbitals. For pure clusters of many transition metals the binding of CO and the influence of cluster size and charge is well studied. We here aim to obtain an understanding of the effects of alloying on the CO activation, using it as a gauge for the change in the electronic structure in terms of the d band level. Results are presented for small alloy clusters composed from Co and Mn atoms.