Hamburg 2009 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 34: Poster II

A 34.6: Poster

Donnerstag, 5. März 2009, 16:30–19:00, VMP 9 Poster

Local electronic structure of exohedral, endohedral, and magic doped silicon clusters — •Jochen Rittmann¹, Marlene Vogel¹, Konstantin Hirsch¹, Andreas Langenberg¹, Philipp Klar¹, Jürgen Probst¹, Robert Richter¹, Fabian Lofink¹, Vicente Zamudio-Bayer¹, Thomas Möller¹, Bernd von Issendorff², and Tobias Lau¹ — ¹Technische Universität Berlin, Institut für Optik und Atomare Physik, EW 3-1, Hardenbergstraße 36, D-10623 Berlin — ²Albert-Ludwigs-Universität Freiburg, Fakultät für Physik, Stefan-Meier-Straße 21, D-79104 Freiburg

Because of its element specific nature, X-ray absorption spectroscopy is a perfect tool to study the local electronic structure of individual constituents of binary clusters. We apply this method to transition metal doped Si_n⁺ clusters in the size range of n=4–19 and show how geometric and electronic structure are interlinked in magic VSi₁₆⁺ and close-to- magic TiSi₁₆⁺ and CrSi₁₆⁺ clusters. The high symmetry of these doped silicon cages is evident from X-ray absorption spectra at the transition metal and silicon 2p edges. Determination of the direct silicon 2p photoionization threshold reveals electronic shell closure and a large HOMO-LUMO gap in VSi₁₆⁺. The transition from exohedral to endohedral doping is reflected in changes of local electronic structure of Sc, Ti, V, Cr, and Mn doped Si_n⁺ clusters. While the local magnetic moment seems to be quenched in TiSi₁₆⁺, VSi₁₆⁺, and CrSi₁₆⁺, we find spectral signatures of a local d⁵ configuration at the Mn dopant in MnSi₁₄⁺, indicating a high magnetic moment in this doped semiconductor cage.