Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 54: Particles and clusters I

O 54.5: Talk

Wednesday, March 16, 2011, 16:00–16:15, WIL C307

CO adsorption on neutral iridium clusters — •Christian Kerpal, Daniel Harding, Gerard Meijer, and André Fielicke — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin

The adsorption of carbon monoxide on neutral iridium clusters in the size range of n=3 to 21 atoms is investigated with infrared multiple photon dissociation spectroscopy. The spectra are obtained by irradiating a molecular beam containing Ir_nCO complexes with intense, tunable IR radiation from the Free Electron Laser for Infrared eXperiments (FELIX) and measuring the changes induced in the mass distribution. For each cluster size only a single ν(CO) band is present with frequencies in the range between 1962 cm⁻¹ (n=8) and 1985 cm⁻¹ (n=18) which can be attributed to an atop binding geometry. This behaviour is compared to the CO binding geometries on clusters of other group 9 and 10 transition metals as well as to that on extended surfaces. The preference of Ir for atop binding is rationalized by relativistic effects on the electronic structure of the later 5d metals.