Gestufte Oberflächen und Quasieindimensionale Strukturen Photoemission an 3d Metallen auf W(110)

The coverage dependent electronic structure of Cu and Co an vicinal W(110) surfaces has been investigated with angle resolved photoelectron spectroscopy. To prepare the quasi-one-dimensional Cu and Co systems the method of step edge decoration of the vicinal W(110) surfaces has been used. The vicinal surfaces with step edges in (110), (100) and (111) direction has been investigated using LEED. From the characteristic spot splitting a terrace width of 11 atom rows was determined. The band structures of the flat and the vicinal surfaces have indicated that the step edges have no bearing an the bulk band structure at k$_{\parallel}$=0. But the surface band structure shows a different dispersion and different energy positions of surface states. An analysis of the W 4$\int_{\frac{\tau}{2}}$ core level spectra has resulted in an additional contribution of the step edges in the spectra of the vicinal surfaces wich a surface core level shift between 120 and 150meV. A Cu and Co coverage dependent investigation of the core levels shows that there is no Co induced surface reconstruction and up to 0.15 monolayer no Cu induced surface reconstruction. In the range of 0.15 and 0.3 monolayer Cu the surface peak shifts to higher binding energies. This is probably a result of a surface reconstruction of the W substrat. In the core level spectra wich Co coverage the intensity of the surface peak decreases linear with Co coverage and the intensity of a new contribution, the interface structure, increases with Co coverage. With Co respectively Cu coverage the contribution of the step edge shifts to lower respectively higher binding energies. This can be attributed to a charge transfer between the adsorbat and the substrat in different directions. For coverages of 0.1 monolayer Co respectively Cu electronic states near the fermi edge has been observed. These states show a dispersion with k$_{\parallel}$ along the step edges but they show no dispersion perpendicular to the step edges. This is the first evidence of a quasi-one-dimensional structure (Co respectively Cu quantum wire) an vicinal W(110) surfaces