Vacant regions were introduced into the (111)-7x7 surface by means of 1keV Ar ion bombardment, and were studied by using scanning tunnelling microscopy. The vacant regions were areas from which adatoms had been removed by ion impact. When the samples were annealed at temperatures of between 500 and 730C, the vacant regions recovered their initial 7x7 structure via a new metastable 7x7 structure which was observed here. Both of the rate-controlling steps were described by single activation free energies with predominant -TS terms, and minor E terms. The activation entropies, S, were found to be -1.9 x 10-3eV/K for metastable 7x7 formation and -2.6 x 10-3eV/K for stable 7x7 formation.

K.Yoneyama, K.Ogawa: Japanese Journal of Applied Physics, 1996, 35[1-6B], 3719-23