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Persistent URL http://purl.org/net/epubs/work/38809
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Record Id 38809
Title Cu-capped surface alloys of Pt/Cu100
Abstract The room temperature deposition of 0.5 ML Pt on Cu{100} followed by annealing to 525 K results in a sharp c(2x2) low energy electron diffraction (LEED) pattern. The structure of this surface alloy is investigated by means of symmetrised automated tensor LEED (SATLEED) analysis and ab-initio plane wave density functional calculations. The results are then compared to those for the similar system: 0.5 ML Pd/Cu{100}. SATLEED results for the Pt/Cu{100} show that it consists of an ordered c(2x2) Cu-Pt second layer alloy capped with a pure Cu first layer. The first and second interlayer spacings are found to be expanded by +5.1?±1.7 % and +3.5?±1.7%, respectively (relative to the bulk Cu interlayer spacing of 1.807 ?Å) due to the insertion of the 8% larger Pt atoms into the second layer. The ordered mixed layer is found to be rippled by 0.08?±0.06 ?Å with Pt atoms rippled outwards towards the solid-vacuum interface. A smaller rippling of 0.03?±0.11 ?Å in the fourth pure Cu layer was also detected with Cu atoms directly underneath Pt atoms rippled towards the second layer Pt resulting in a Pt-Cu bond length of 2.52 ?Å which compares to the sum of metallic radii of 2.67 ?Å. A recent quantitative SATLEED analysis for the 0.5 ML Pd/Cu{100} was performed in an earlier study (C.J. Barnes et al., Surf. Sci. 492 (2001) 55). A similar structure to the Pt/Cu{100} has been retrieved with slight differences in the interlayer spacings. The ab-initio density functional results are fully consistent with the experimentally determined structures. However, they reveal an interesting difference between the stability of the Pd and Pt systems and highlight the fact that the Pd/Cu structure is best thought of as meta-stable structure occurring as an intermediate step in the diffusion of the transitional metal ion into the bulk of the Cu substrate.
Organisation CCLRC , CSE , CSE-CMSG
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Language English (EN)
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Journal Article J Phys-Condens Mat 15, no. 12 (2003): 1879-1887. doi:10.1088/0953-8984/15/12/305 2003