Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 53: Poster Session - Oxides and Insulators: Adsorption and Reaction of Small Molecules

O 53.4: Poster

Tuesday, March 17, 2020, 18:15–20:00, P2/1OG

Quantitative LEED studies of acetylene physisorbed on ionic surfaces – significance of electron scattering from hydrogen — •Jochen Vogt — Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg

C₂H₂ physisorption on ionic substrates is characterized by comparably soft interaction, leaving the internal structure of the molecules largely undistorted. On the KCl(100) surface, the first layer has (√2×√2)R45^∘ symmetry [1], while on the NaCl(100) surface, (3√2×√2)R45^∘ and even (7√2×√2)R45^∘ phases have been observed [2]. In principle, a complete structure determination of such systems is possible using LEED I(V) analysis [3,4]. Due to the weakness of electron scattering from hydrogen, this element was not included in a LEED study of C₂H₂-(2×2)/MgO(100) [4]. The contribution addresses the possible systematic error resulting from the neglect of hydrogen scattering in these systems. In the case of C₂H₂/KCl(100), calculated I(V) curves of the very weak superstructure spots are significantly affected by the neglect of hydrogen with respect to both intensity and the position of maxima, the latter implying notable changes of the Pendry R-factor. [1] A. L. Glebov et al., Phys. Rev. B61(2000), 14028 [2] S. Picaud et al., Phys. Rev. B57 (1998), 10090 [3] J. Vogt, H. Weiss, Phys. Rev. B77 (2008), 125415 [4] D. Ferry et al., Phys. Rev. Lett. 78 (1997), 4237