Interestingly, not long before the Wahlstrom 56 experiment, Fig. A close-up of two adatoms at a distance of about 64 Å from each other; note that the atoms seem to share local density of states oscillations with each other. Reprinted with permission from Wahlstrom et. al. Avouris and co-workers have observed that metal-on-metal epitaxy formed Ag islands on Ag(111) have a radius of approx. 45 Å. Such size is close to three times the period of oscillations expected for 2D electron gas (approx. 18 Å), hinting at a possible FO origin. The size difference in comparison with three oscillation periods (54 Å) can be explained, taking into account that such islands can be described by a mixture of two-electron states .