ARPEFS as an analytic technique [electronic resource].

Published:: Washington, D.C. : United States. Dept. of Energy, 1991.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description:: Pages: (152 pages) : digital, PDF file
Additional Creators:: Lawrence Berkeley National Laboratory, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information

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Summary:

Two modifications to the ARPEFS technique are introduced. These are studied using p(2 × 2)S/Cu(001) as a model system. The first modification is the obtaining of ARPEFS χ(k) curves at temperatures as low as our equipment will permit. While adding to the difficulty of the experiment, this modification is shown to almost double the signal-to-noise ratio of normal emission p(2 × 2)S/Cu(001) χ(k) curves. This is shown by visual comparison of the raw data and by the improved precision of the extracted structural parameters. The second change is the replacement of manual fitting of the Fourier filtered χ(k) curves by the use of the simplex algorithm for parameter determination. Again using p(2 × 2)S/Cu(001) data, this is shown to result in better agreement between experimental χ(k) curves and curves calculated based on model structures. The improved ARPEFS is then applied to p(2 × 2)S/Ni(111) and (√3 × √3) R30°S/Ni(111). For p(2 × 2)S/Cu(001) we find a S-Cu bond length of 2.26 Å, with the S adatom 1.31 Å above the fourfold hollow site. The second Cu layer appears to be corrugated. Analysis of the p(2 × 2)S/Ni(111) data indicates that the S adatom adatom adsorbs onto the FCC threefold hollow site 1.53 Å above the Ni surface. The S-Ni bond length is determined to be 2.13 Å, indicating an outwards shift of the first layer Ni atoms. We are unable to assign a unique structure to (√3 × √3)R30°S/Ni(111). An analysis of the strengths and weaknesses of ARPEFS as an experimental and analytic technique is presented, along with a summary of problems still to be addressed.

Report Numbers:

E 1.99:lbl-30769
lbl-30769

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Note:

Published through SciTech Connect.
04/01/1991.
"lbl-30769"
"DE91014237"
Schach von Wittenau, A.E.

Funding Information:

AC03-76SF00098

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