Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 94: Methods: Other Experimental Techniques II

O 94.5: Talk

Friday, February 29, 2008, 13:00–13:15, MA 141

Stereographic intensity maps of elastically backscattered electrons in directional elastic peak electron spectroscopy — •Irek Morawski and Marek Nowicki — Institute of Experimental Physics, University of Wrocław, pl. M. Borna 9, PL 50-204 Wrocław, Poland

The full hemispherical intensities of elastically backscattered electrons from Au(111) were measured using directional elastic peak electron spectroscopy (DEPES) [1] at primary electron beam energies in the range from 0.5 till 2.0 keV. The enhancement of recorded intensities is observed when the primary electrons strike the crystalline sample along the close packed rows of atoms. Experimental stereographic intensity maps reveal a three-fold symmetry of the substrate, which gives straightforward identification of the sample crystalline structure. Theoretical intensity distributions were obtained using multiple scattering (MS) calculations [2]. In calculations different scattering orders were taken into account. An R-factor analysis of experimental and theoretical patterns reveals a significant role of the higher scattering order leading to the defocusing effect along the closest-packed rows of atoms. A contribution of particular sample layers to the recorded signal as well as application of the total electron mean free path instead of so far used values of the inelastic mean free path in calculated MS intensities are discussed.

[1] S. Mróz, M. Nowicki, Surf. Sci. 297 (1993) 66.

[2] I. Morawski, M. Nowicki, Phys. Rev. B 75 (2007) 155412