The scanning tunnelling microscopy of laser-irradiated (100) surfaces showed that the dimerized outermost layer could be selectively removed by pulsed laser light at a fluence that was below the melting threshold. The atoms in the laser-exposed second layer were close to the positions of a bulk terminated 1 x 1 structure, but with a slight pairing, while the dimers retained a 2 x 1 configuration in the first layer. It was found that the pairing distance, and fraction of remaining dimers, decreased with increasing laser exposure. The laser-exposed layer also remained free from vacancies.

J.Xu, S.H.Overbury, J.F.Wendelken: Physical Review B, 1996, 53[8], R4245-8