Scanning tunneling microscopy at low temperature reveals that upon dissociative adsorption of oxygen on Ag(001) "hot" adatoms have separated in a far-ranged transient motion to two different intrapair distances around 2 and 4 nm, corresponding to 7 and 14 surface lattice constants, respectively. Manipulation experiments on oxygen atoms displaying different contrasts in the images and model calculations suggest that the transient motion ends up not only in the stable fourfold hollow site but also in two metastable sites. (C) 2001 American Institute of Physics.