Low-Energy Electron Diffraction Studies of Oxygen Adsorption and Oxide Formation on a (001) Iron Surface

The technique of low‐energy electron diffraction (LEED) has been used to study oxygen adsorption and oxide formation on a (001) surface of iron. The LEED data indicated that the atomically clean iron (001) surface was an unreconstructed surface. The chemisorbed oxygen layer formed on exposing the clean face of iron to very low oxygen partial pressures consisted of half a monolayer of oxygen atoms arranged in a Fe (001) c(2×2)‐O two‐dimensional array. With continued oxygen exposure and annealing, a thin layer of was observed to form on the iron crystal with its (001) face oriented parallel to the (001) face of the iron substrate, and with the [110] direction of the parallel to the [100] direction of the iron. These films that were formed and maintained at very low oxygen partial pressures were stable at room temperature.