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Multilayer rippled structure of the NiAl(110) surface: a medium energy ion scattering study
A182 556
Surface Science 183 (1987) 556-564 North-Holland, Amsterdam
MULTILAYER RIPPLED STRUCTURE OF THE NiAI(ll0) A MEDIUM ENERGY ION SCATrERING STUDY S.M. YALISOVE
SURFACE:
and W.R. GRAHAM
Department of Materials Science and Engineering, Laborato~ for the Research on the Structure of Matter, University of Pennsylvania, Philadelphia, PA 19104, USA Received 18 August 1986; accepted for publication 5 December 1986 The NiAI(ll0) surface structure has been studied with medium energy ion scattering in a channeling and blocking (MEIS/CB) experiment. A high sensitivity to the first layer ripple (10% ripple with the A1 on top) is reported and a multilayer model is proposed, The first layer Ni atoms are contracted relative to the second layer Ni atoms by 7%, and the second layer Ni atoms are expanded relative to the third layer Ni atoms by 1%. The first layer AI atoms are expanded relative to the second layer AI atoms by 5%, and the second layer AI atoms are contracted relative to the third layer A1 atoms by 1%. The model assumes bulk-like positions of the third layer for both Ni and AI atoms. The present results are in excellent agreement with a recent single layer LEED intensity analysis.
Surface Science 183 (1987) 565-575 North-Holland, Amsterdam
565
THE SEGREGATION IN SINGLE CRYSTAL Ni-Pt A MODEL FOR MULTILAYER SEGREGATION L. D E T E M M E R M A N
*, C. C R E E M E R S ,
ALLOYS:
H. VAN HOVE and A. NEYENS
Fysico-Chemisch Laboratorium, Celestijnenlaan 200G, B-3030 Leuven, Belgium Received 27 October 1986; accepted for pubfication 16 December 1986 Equilibrated (111) surfaces of Ni-Pt single crystal alloys terminate with a Pt-enriched layer. A multilayer segregation model including a Pt-Pt bond strengthening accounts well for the observed results.
576 NEXAFS
Surface Science 183 (1987) 576-590 North-Holland, Amsterdam DETERMINATION
PLATINUM SURFACE J.S. S O M E R S , T h . L I N D N E R ,
OF CO ORIENTATION M. SURMAN
ON A STEPPED
*, A . M . B R A D S H A W
Fritz-Haber-lnstitut der Max-Planck-Gesellschaft, Faradayweg 4-6, 1000 Berlin 33, Germany G.P. WILLIAMS
**
Berliner Elektronenspeicherringgesellschaft ]~r Synchrotronstrahlung mbH (BESS Y), Lentzeallee 100, 1000 Berlin 33, Germany
Surface Science 183 (1987) 556-564 North-Holland, Amsterdam
MULTILAYER RIPPLED STRUCTURE OF THE NiAI(ll0) A MEDIUM ENERGY ION SCATrERING STUDY S.M. YALISOVE
SURFACE:
and W.R. GRAHAM
Department of Materials Science and Engineering, Laborato~ for the Research on the Structure of Matter, University of Pennsylvania, Philadelphia, PA 19104, USA Received 18 August 1986; accepted for publication 5 December 1986 The NiAI(ll0) surface structure has been studied with medium energy ion scattering in a channeling and blocking (MEIS/CB) experiment. A high sensitivity to the first layer ripple (10% ripple with the A1 on top) is reported and a multilayer model is proposed, The first layer Ni atoms are contracted relative to the second layer Ni atoms by 7%, and the second layer Ni atoms are expanded relative to the third layer Ni atoms by 1%. The first layer AI atoms are expanded relative to the second layer AI atoms by 5%, and the second layer AI atoms are contracted relative to the third layer A1 atoms by 1%. The model assumes bulk-like positions of the third layer for both Ni and AI atoms. The present results are in excellent agreement with a recent single layer LEED intensity analysis.
Surface Science 183 (1987) 565-575 North-Holland, Amsterdam
565
THE SEGREGATION IN SINGLE CRYSTAL Ni-Pt A MODEL FOR MULTILAYER SEGREGATION L. D E T E M M E R M A N
*, C. C R E E M E R S ,
ALLOYS:
H. VAN HOVE and A. NEYENS
Fysico-Chemisch Laboratorium, Celestijnenlaan 200G, B-3030 Leuven, Belgium Received 27 October 1986; accepted for pubfication 16 December 1986 Equilibrated (111) surfaces of Ni-Pt single crystal alloys terminate with a Pt-enriched layer. A multilayer segregation model including a Pt-Pt bond strengthening accounts well for the observed results.
576 NEXAFS
Surface Science 183 (1987) 576-590 North-Holland, Amsterdam DETERMINATION
PLATINUM SURFACE J.S. S O M E R S , T h . L I N D N E R ,
OF CO ORIENTATION M. SURMAN
ON A STEPPED
*, A . M . B R A D S H A W
Fritz-Haber-lnstitut der Max-Planck-Gesellschaft, Faradayweg 4-6, 1000 Berlin 33, Germany G.P. WILLIAMS
**
Berliner Elektronenspeicherringgesellschaft ]~r Synchrotronstrahlung mbH (BESS Y), Lentzeallee 100, 1000 Berlin 33, Germany