Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 50: Poster: Nanostructures on Surfaces II
O 50.1: Poster
Dienstag, 13. März 2018, 18:15–20:30, Poster B
Vibrational properties of the Au-(√3×√3)/Si(111) surface reconstruction — •S. Sanna1, M. Krenz2, S. Neufeld2, W. G. Schmidt2, E. Speiser3, J. Räthel3, S. Chandola3, N. Esser3, B. Halbig4, M. Liebhaber4, U. Bass4, and J. Geurts4 — 1Institut für Theoretische Physik, Justus-Liebig-Universität Gießen — 2Department Physik, Universität Paderborn — 3Leibniz-Institut für Analytische Wissenschaften, Berlin — 4Physikalisches Institut, Experimental Physics 3, Universität Würzburg
The atomic structure of the Au-induced √3×√3 reconstruction of the Si(111) surface has been controversially discussed for two decades. Different structural models have been proposed to explain the observed STM Pattern [J. Phys. Condens. Matter 27, 475001 (2015)]. While the proposed structural models are almost energetically degenerate, the analysis of the vibrational properties might help to assign a structural model to the surface reconstruction. Our first principles calculations within density functional theory predict surface localized phonon modes for all investigated structures. However, the calculated Raman spectra are model-dependent. Corresponding surface Raman measurements reveal the presence of vibrational eigenmodes in the spectral range from 20 to 450 cm−1, which are compatible with the frequencies calculated for the conjugate honeycomb-chained-trimer model (CHCT) [Surf. Sci. 275, L691 (1992)]. On the basis of the phonon eigenfrequencies, symmetries, and Raman intensities, we assign the measured spectral features to the calculated phonon modes.