Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 7: Metal Substrates: Adsorption I

O 7.4: Vortrag

Montag, 26. März 2007, 12:00–12:15, H39

Dispersion of the O(2x1) Cu(110) surface phonons — •Klaus Brüggemann and Harald Ibach — IBN-3 Forschungszentrum Jülich , Leo-Brandt-Str. , D-52428 Jülich

In the past the O(2x1) Cu(110) surface was investigated by serveral groups(1) with the main focus on the formation of the (2x1)superstructure built by the CuO-Chains. In this work we present the measurements of the dispersion of the CuO surface phonons. The surface of the Cu single crystal was oxidized with 6 Langmuir Oxygen so that it was fully covered with 1ML of CuO. After annealing to 660K the energy loss spectra of the ordered layer were measured by an HREELS Spectrometer (2) built in our Institute. The scattering plane of the electron beam laid along the [001] and [1-10] directions. In that way we were able to determine the dispersion of the suface phonons along Gamma to Y and Gamma to X of the Brillouin zone. It turned out that the phonon vibration could be tracked at an electron energy of ca. 50eV. In the Gamma to Y direction we measured a TO mode starting at a wavenumber of 750 1/cm in Gamma and ending with 690 1/cm in Y. In the Gamma to X direction was a LO mode starting at 400 1/cm in Gamma and ending with 370 1/cm in X.

(1)H.Ibach et al., Phys. Rev. B 72, 245408 (2005) ; K. Kern et al., Phys. Rev. Lett. 67, 855 (1991) ; O.Skibbe et al. Phys. Rev. B 66, 235418 (2002)

(2)H. Ibach, Electron Energy Loss Spectrometers, Springer Series in Optical Sciences Vol. 63 (Springer, Berlin 1991)