Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: Nanostructures at Surfaces
O 35.9: Poster
Dienstag, 17. März 2015, 18:15–21:00, Poster A
Deposition of mass selected clusters produced with the THErmal CLuster Apparatus (THECLA) — •Andreas Gruhn, Stefanie Roese, Jens-Christian Meyer, David Engemann, and Heinz Hövel — Fakultät Physik / DELTA, TU Dortmund, Germany
The clusters in THECLA are produced in a supersonic nozzle expansion [1][2]. In this case the clusters have a mass distribution and a narrow velocity distribution. A typical cluster consists of (2.5 ±1.72.8)· 102 atoms and has a velocity of 1.3 · 103 m/s. It is a matter of particular interest to have a mass selected cluster beam. In the source the clusters are partially ionized. The ion current is increased by a hot-cathode plasma ionisation [3]. Because of their charge, the cluster ions can be mass selected by deflection in a transverse electric field. The ion current is measured with a moveable Faraday cup. After deposition on substrates, the clusters can be characterized by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The quality of mass selection is determined by comparing the results and the mass spectrum of the source. Based on the measurements and simulations, the ion optics is optimized. The goal is to achieve maximum quality of the mass selection with a sufficient high ion current. This allows more accurate measurements of properties depending on the cluster size.
[1] O. F. Hagena, Z. Phys. D 20, 425 (1991). [2] H. Hövel et al., Phys. Rev. B 48, 18178 (1993). [3] I. M. Goldby et al., Rev. Sci. Instrum. 68, 3327 (1997).