Book of Abstracts Book of Abstracts - Universität Konstanz

A - 4
Structure Determination of Small Silver Cluster Ions by Trapped Ion
Electron Diffraction
106
Detlef Schooss 1 , Martine N. Blom 1 , Lars Walter 1 , Mattias Kordel 1 , Jason Stairs 1 , Joel H. Parks 2 and
Manfred M. Kappes 1,3
1 Institute of Nanotechnology, Forschungszentrum Karlsruhe,D-76021 Karlsruhe, Germany
2 The Rowland Institute at Harvard, Cambridge, MA 02142, USA
3 Institut für Physikalische Chemie, Universität Karlsruhe, D-76128 Karlsruhe, Germany
The structure of silver clusters ions is studied by the recently developed technique of
trapped ion electron diffraction (TIED) [1]. In brief, cluster ions are generated by a magnetron
sputter source [2] and injected into a Paul ion trap. After mass selection and thermalization the
trapped ions are irradiated with a 40 keV electron beam and the resulting diffraction pattern is
integrated with a CCD detector. The sensitivity and resolution of the apparatus is documented
by figure 1 which shows the molecular scattering function obtained for Ag55 + at 90K.
+
Figure 1: Experimental diffraction pattern (open squares) of mass selected Ag55 at 90K. The measurement is
consistent with an icosahedral structure as calculated from RIDFT calculations (line).
Comparison to RIDFT structure calculations for various trial geometries reveals that the cluster
ensemble which was probed comprises predominantly icosahedral Ag55 + . TIED measurements
at different cluster sizes and charge states (Ag19 +/- to Ag79 +/- ) at a variety of temperatures ranging
from 100 - 650 K are presently ongoing.
References
[1] M. Maier-Borst, D. C. Cameron, M. Rokni and J. H. Parks, Phys. Rev. A, 59, R3162 (1998), S.
Krückeberg, D. Schooss, M. Maier-Borst, J. H. Parks, Phys. Rev. Lett. 85(21), 4494-4497 (2000)
[2] H. Haberland, M. Mall, M. Moseler, Y. Qiang, T. Reiners and Y. Thurner, J. Vac, Sci. Technol.
A 12(5), 2925 (1994)