To understand this issue better, we turn our attention to the dissociative chemisorption of O 2 on Cu(110), which is a well-studied system. Previous literature firmly establishes that after dissociation, the O-atom coverage saturates at 0.5 ML, forming a (2×1) overlayer. It is also known that prolonged exposure to O 2 (10 5 Langmuir) leads to the formation of a new (6×2) O-Cu structure with 0.66 ML O-atom coverage, similar to what we see at higher incident energies. A similar situation has also been reported for the N 2 /W(110) system. In this work, it was reported that the saturation coverage is 0.25 ML at an energy of 0.1 to 1 eV. At higher incidence kinetic energies (2 eV), this saturation coverage increases to around 0.5 ML. Low-energy electron diffraction (LEED) studies 39 revealed a p(2×2) structure at 0.25 ML coverage and c(4×2) structure at 0.5 ML coverage. In light of the above points, we attribute the increased surface coverage at higher E i to specific surface sites having a higher activation barrier for dissociation becoming accessible at E i beyond 3 eV.