The quenching technique was used to estimate the formation energy of an ad-vacancy on the Pt(111) surface. These ad-vacancies coagulated into clusters, forming monoatomic 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 the atomic step loops covering the surface. The obtained value of ad-vacancy formation energy was about 0.62eV on the assumption that the relation for the bulk crystal could also be applied to crystal surface phenomena.

Estimation of Ad-Vacancy Formation Energy on the Pt(111) Surface by using Reflection Electron Microscopy. Y.Uchida, G.Lehmpfuhl: Surface Science, 1991, 243[1-3], 193-8