低速イオン散乱法 (ICISS) によるAu-Cu系合金単結晶表面の構造および組成

概要

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Surface structures and comopositions of Au3Cu(001) and Au9Cu(001) were investigated by means of impact collision ion scattering spectroscopy (ICISS). The experimental results were assessed by a recently developed numerical computer simulation. At room temperatures, both surfaces revealed unreconstructed (1×1) structures, but with about 10% contraction of the interlayer spacing between the first and second layers. The topmost layers of both surfaces were found to be occupied mostly by Au atoms. For the second layer, the Cu concentration was estimated to be close to the full occupancy in the case of Au3Cu(001) and about one-half in the case of Au9Cu(001). With respect to the unreconstructed Au9Cu(001), the second AuCu layer was suggested to be in a disordered state. At an eleveted temperature about 350°C, a reversible transformation from the unreconstructed (1×1) to reconstructed (5×1) -like structure was observed where the topmost layer of the reconstructed surface was simulated using a monoatomic layer of quasi-hexagonal net corresponding to the (5×1) structure.
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