Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 24: Particles and clusters

O 24.1: Vortrag

Dienstag, 23. März 2010, 10:30–10:45, H34

Not so loosely bound: temperature dependent vibrational fingerprints of AuNKrM clusters — •Luca M. Ghiringhelli, Philipp Gruene, Gerard Meijer, Andrè Fielicke, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

In order to interpret the vibrational spectra of neutral AuNKrM clusters, as measured in a Multiple Photon Dissociation Far-IR experiment (P. Gruene et al., Science 321, 674 (2008)), we calculated their finite temperature vibrational spectra, by means of all electron density functional theory, including the Tkatchenko-Scheffler van der Waals correction. We surprisingly find that Kr forms weak chemical bonds (binding energy around 0.2 eV per Kr atom) with 1- to 3-fold coordinated Au atoms belonging to small AuN clusters (N ≤ 4). Such AuNKrM clusters have a vibrational spectrum which is different from the related AuN clusters. For bigger AuN clusters, Kr physisorbs to the clusters, forming a complex whose vibrational spectrum is practically identical to the spectrum of the bare cluster. Anharmonicities affect the spectrum by changing (with respect to the harmonic spectrum) the relative intensity of the peaks and by showing new peaks, due to interactions among eigenmodes.

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