Röntgenspektroskopie an freien größenselektierten Siliziumclustern, dotierten Siliziumclustern und Aluminiumclustern [article]

Marlene Vogel, Thomas Möller, Technische Universität Berlin, Technische Universität Berlin
2010
Atomic clusters, as systems sized in a range between a few atoms and several thousand atoms, are the link between the single atom on the one side and the bulk material on the other. They exhibit special properties, which are fundamentally different from those of the atom or the bulk material. Understanding these properties and what is causing them allows fundamental insight into the processes relevant for the evolution of the properties starting from the atomic system via the differently seized
more » ... differently seized clusters as intermediate steps and finally towards the bulk. Furthermore the special cluster properties are by themselves interesting for future technological innovations. Studying the fundamental properties of the clusters, without any influencing effects from a surrounding or adjacent substrate, is only possible in the gas phase. Spectroscopy by X-ray photons has the advantage that the core-levels of the clusters are accessible and thus X-ray spectroscopy is a local and element specific method. Therefore this method is especially suitable for investigating clusters of mixed materials. However, due to the low target density inside the free cluster beam and the relatively low photon flux for X-ray photon sources, investigating free clusters with X-ray spectroscopy is a quite challenging task. In this thesis an experimental setup is presented, which allows for the first time X-ray spectroscopy on free size-selected metal- and semiconductor-clusters at a synchrotron facility. The method used is ion-yield spectroscopy, which allows for separately analyzing the resonant and direct part of the core-level photoionization. As will be shown, this method can be used for an investigation of the clusters which provides similar information as X-ray photoelectron spectroscopy (XPS). The results of 2p core-level excitation are presented for three different cluster types, pure silicon clusters Sin+ in the size range n = 5-92, doped silicon clusters MSin+, with transition metal atom M = Ti, V, Cr and n = 15-17 plus ScSi16+, and pure alumi [...]
doi:10.14279/depositonce-2411 fatcat:yfx7olbtqjhdrpp5svs72ypyyy