Atomic reconstruction of metal surfaces

It is now well established that the structure of a thermally equilibrated surface may be quite different from that obtained by simply truncating a solid.10 Surface atoms may rearrange to form a structure according to the lowest surface free energy of that surface. The determination of the atomic structure of solid surfaces is one of the important endeavors in surface science, as the atomic structure will decide both the physical and the chemical properties of the surfaces. Surface reconstruction will also play an important role in the crystal growth and epitaxy of thin films. 

Macroscopic experiments, both reciprocal-space techniques and direct-space techniques, conclude that the (110) surfaces of Pt, Ir and Au reconstruct to a (1 x 2) structure.30 Several atomic models have been proposed,31 of which the simple missing row model agrees better with various experimental data. In this model every other [110] atomic row is missing from the reconstructed (1 X 1) surface. To transform a (1 x 1) 

Thus the simple missing model is the correct model. 

To be able to observe directly each atomic jump of the atomic 

1000 to 1200 K, impurity atoms, mostly sulfur, segregate to the surface. Vanselow Munschau48 also find that impurity segregation can be observed in a similar temperature range even for Pt tips of five nine purity. It is no wonder that the FIM result obtained by Tsong Gao47 is very different from that obtained by Witt Muller. 

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