Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 40: Elektronische Struktur V
O 40.5: Vortrag
Freitag, 28. März 2003, 12:15–12:30, M\"UL/ELCH
Surface dynamics of Mo(110)-H and Mo(110)-Li — •Jörg Kröger1, Sieghart Lehwald2, and Harald Ibach2 — 1Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany — 2Institut für Schichten und Grenzen, Forschungszentrum Jülich, D-52425 Jülich, Germany
Both adsorbate systems exhibit severe substrate surface phonon anomalies at a critical wave vector along [001]. It was demonstrated by experiment and theory that the phonon anomaly of Mo(110)-H is of the Kohn type. The anomaly of Mo(110)-Li, however, remained obscure. The dispersion of adsorbate phonons enlightens the obscurity: whereas the adsobate phonon of Mo(110)-Li disperses weakly along [001], we observe an anomalous indentation of an adsorbate phonon of Mo(110)-H. This indentation is due to the Kohn effect as we found recently. Thus we are plied with a criterion, which decides whether the substrate surface phonon anomaly is of the Kohn type or not: for a Kohn anomaly of substrate surface phonons to occur an adsorbate phonon must necessarily be affected by the Kohn effect. Consequently we rule out the observed substrate surface phonon anomaly to be driven by the Kohn effect.