Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 32: Oxides and Insulators: Clean Surfaces

O 32.4: Vortrag

Dienstag, 26. Februar 2008, 13:45–14:00, MA 042

Tensor LEED study of the surface relaxation and lattice dynamics of RbI(100) and RbBr(100) — •Stephan Härtel, Jochen Vogt, and Helmut Weiss — Chemisches Institut der Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, D-39106 Magdeburg

During the last decade the surfaces of several alkali halides were investigated by LEED and other experimental techniques. In good agreement with theoretical predictions for many compounds a rumpling as well as a contraction of the first interlayer distance was found. Up to now no LEED data of the rubidium halides were available. In the present work RbI(100) and RbBr(100) were investigated by means of LEED in an energy range from 30 to 220 eV. The recorded I(E) data were analyzed using the tensor LEED approach. RbI(100) exhibits a slight rumpling where the Rb⁺ are shifted inward by 0,07±0,03 Å and the I⁻ outward by 0,02±0,01 Å. There is no significant contraction of the interlayer distance. In contrast to theoretical calculations [1] the lattice amplitudes of the ions of the two topmost layers are not enlarged significantly compared to the bulk values. For RbBr(100) also a rumpling was observed which is however smaller than that of RbI. The first interlayer distance is reduced by about 1.5%. Different from RbI the lattice amplitudes in the two topmost layers are enlarged by a factor of 1.3 for Rb⁺ and 1.25 for Br⁻.

[1] de Wette, F.W. et al.: New surface mode on the (001) surfaces of RbBr and RbI, Physical Review B, 35, 5 (1987)