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Regensburg 2000 – scientific programme

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O: Oberflächenphysik

O 19: Epitaxie und Wachstum (IV)

O 19.6: Talk

Tuesday, March 28, 2000, 17:30–17:45, H36

Reversible Phase Transitions of Gold Submonolayers on a Re(10-10) Surface — •Antje Vollmer1, Dschun Song2, Dirk Rosenthal2, Sven L.M. Schroeder2, and Klaus Christmann21FU Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin — 2FU Berlin, Institut für Chemie, Takustraße 3, 14195 Berlin

Thin Au films on Re(10-10) have been studied as a function of surface coverage in the temperature range from 300 K to 900 K by means of Video-LEED, AES and XPS. A coverage calibration was achieved by a combination of AES uptake curves and the interpretation of characteristic LEED patterns. Immediately after deposition of Au, metastable (1x4)- and (1x5)-structures are observed at coverages from 0.25 to 0.8, and from 0.8 to 0.9, respectively. However, formation of (1x1)-islands can be observed within less than an hour. For coverages between 0.5 and 0.7 ML, heating to 900 K leads to a (1x3)-superstructure that, upon cooling below 700 K, re-forms the (1x4)-structure observed after deposition at 300 K. In the monolayer range a (1x1)-structure is observed, in which the troughs of the Re surface are filled with Au atoms. For the second Au layer, a hexagonal Au film is formed, leading to a (1x8) superstructure. This (1x8) structure is visible up to coverages of 10 ML, even though it is superimposed by a (2x1) phase (possibly due to a reconstruction of the topmost Au layer) after completion of the second layer. The absence of significant core level shifts in XP-spectra of deposited Au submonolayers indicates weak electronic interactions. These are likely to be the underlying cause of the high mobility of Au on Re(10-10), facilitating the reversible phase transitions.

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