Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 24: Postersitzung (Epitaxie und Wachstum, Oxide und Isolatoren, Elektronische Struktur, Oberfl
ächenreaktionen, Adsorption an Oberfl
ächen, Organische Dünnschichten)

O 24.58: Poster

Mittwoch, 26. März 2003, 14:30–17:30, P1

Surface Phonons of H:C(001)-(2x1) and D:C(001)-(2x1) — •Albert Mazur and Johannes Pollmann — Institut für Festkörpertheorie, Universität Münster, Wilhelm-Klemm-Str. 10, D-48149 Münster

Very recently, surface vibrational properties of hydrogen- and deuterium-terminated C(001)-(2x1) surfaces have been studied by HREELS measurements [1]. To contribute to an interpretation of the data, we have calculated surface phonon spectra of D:C(001)-(2x1) and of H:C(001)-(2x1) on equal footing. Our calculations are based on a semiempirical total energy ansatz allowing to calculate atomic force constants on sufficiently many layers at and near the surface. For good convergence of the calculated spectral densities, very thick slabs are then constructed by filling their centers with a large number of bulk-like layers. Employing slabs with up to 436 layers in total, we have carried out a systematic analysis of vibrational features of the D:C(001)-(2x1), as well as, H:C(001)-(2x1) surface. The outcome of our calculations is in very good agreement with the experimental results allowing for a detailed interpretation of the HREELS data [1]. Analyzing the calculated phonon spectral densities with respect to the symmetry of the surface yields valuable insight into the physical origin and nature of the measured surface modes. To better understand the relation between H- and D-induced vibrational surface features, we have studied adlayer systems, in addition, with hypothetical adatoms whose masses range from 1 amu (H) to 2 amu (D).

[1] M. Nishijima and S. Thachepan, private communication