Rostock 2019 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 29: Cluster III (joint session MO/A)

A 29.1: Hauptvortrag

Donnerstag, 14. März 2019, 10:30–11:00, S HS 001 Biologie

Optical spectroscopy of small metal clusters: a deeper look at Au₄⁺ — •Marko Förstel, Wolfgang Schewe, and Otto Dopfer — TU Berlin, IOAP, Hardenbergstr. 36, 10623 Berlin

The catalytic properties of small metal clusters strongly depend on local structure. This is especially the case for very small clusters, where every new atom changes the physical and thus catalytic properties tremendously. For example, gold clusters show catalytic properties at sizes down to three atoms!

With a new setup we were able to measure the optical absorption spectrum of such small gold clusters in hitherto unavailable quality.^[1] These spectra allow for the first time to directly access the structure of the ground and excited state via comparison of the measured vibrational frequencies and Franck-Condon progressions to those from calculated structures. Surprisingly, we find that the optical spectrum cannot be explained by assuming that it stems solely from the rhombic ground state structure of Au₄⁺.^[2]

[1] M. Förstel, B. K. A. Jaeger, W. Schewe, P. H. A. Sporkhorst, O. Dopfer, Improved tandem mass spectrometer coupled to a laser vaporization cluster ion source Rev. Sci. Instr. 2017, 88, 123110.

[2] M. Förstel, W. Schewe, O. Dopfer, Optical spectroscopy of the Au₄⁺ cluster: Resolved vibronic structure indicates an unexpected isomer, submitted.