The quenching technique which was generally used to study lattice defects in metals was here used to estimate the formation energy of an ad-vacancy on the Pt(111) surface. The ad-vacancies coagulated into clusters and formed monatomic step depression islands during cooling. They could be imaged, by reflection electron microscopy, as atomic step loops. The concentration of ad-vacancies at high temperatures could be deduced from the total area of atomic step loops which covered the surface. The estimated ad-vacancy formation energy was about 0.62eV; assuming that the relationship for bulk crystals could also be applied to crystal surface phenomena.

Y.Uchida, G.Lehmpfuhl: Surface Science, 1991, 243[1-3], 193-8