SPring-8, the large synchrotron radiation facility

Speaker : Prof. Dr. Bernd v. Issendorff

Language : English

Affiliation : Faculty of Mathematics and Physics, The University of Freiburg, Germany

Title : The electronic structure of simple and not so simple metal clusters

Abstract:
Clusters allow to follow the development of material properties from the atom to the bulk, but often exhibit characteristics far from that of the atoms or the bulk, which makes them especially interesting. Recent technologic developments make it now possible to study free clusters with well defined size and temperatures down to a few Kelvin. Furthermore the range of spectroscopic tools has been extended, for example by the inclusion of angle resolved photoelectron spectroscopy or gas phase x-ray absorption measurements. Photoelectron spectroscopy on free metal clusters yields is a powerful technique which in principle yields an image of the electronic density of states of the cluster. In the case of simple metals like the alkalis or noble metals this density of states is dominated by electron shell effects, but clearly exhibits an influence of the geometric cluster structure as well [1]. Recently we could show by angle resolved photoelectron spectroscopy that despite this perturbing influence of the ionic background the valence electrons in a close to spherical cluster strongly resemble angular momentum eigenstates [2]. Core shell x-ray absorption spectroscopy (XAS) is an element specific technique, which allows to study the local electronic structure of the atoms addressed [3]. Finally the measurement of x-ray magnetic circular dichroism, which can be achieved by performing XAS-experiments with circularly polarized light on cold free size-selected clusters stored in an ion trap within a strong magnetic field, can be used to measure the spin and orbital moment of single doping atoms or whole clusters, and thus shed some light on the development of the magnetic behavior especially of 3d-transition metals clusters or impurities [4,5].

[References]
[1] O. Kostko, B. Huber, M. Moseler, and B. v. Issendorff, Phys. Rev. Lett. 98, 043401 (2007)
[2] C. Bartels, C. Hock, J. Huwer, R. Kuhnen, J. Schwöbel, B. von Issendorff, Science 323, 1323 (2009)
[3] J. T. Lau, J. Rittmann, V. Zamudio-Bayer, M. Vogel, K. Hirsch, Ph. Klar, F. Lofink, T. Möller, and B.v.Issendorff, Phys. Rev. Lett. 101, 153401 (2008)
[4] M. Niemeyer, K. Hirsch, V. Zamudio-Bayer, A. Langenberg, M. Vogel, M. Kossick, C. Ebrecht, K. Egashira, A. Terasaki, T. Möller, B. v. Issendorff and J. T. Lau, Phys. Rev. Lett. 108, 057201 (2012)
[5] K. Hirsch, V. Zamudio-Bayer, A. Langenberg, M. Niemeyer, B. Langbehn, T. Möller, A. Terasaki, B. v. Issendorff, and J. T. Lau, Phys. Rev. Lett. 114, 087202 (2015)

Organizer : Kensuke Tono
Mail : tono@spring8.or.jp
PHS : 3321