Growth of iron oxides on the Fe(111) surface precovered with sulphur and/or potassium

The oxidation process of the iron surface precovered with sulphur and/or potassium has been studied using the AES method. Sulphur has an inhibiting effect on the rate of the oxidation process at the beginning, but when the layer of the iron oxide is formed, the inhibiting effect of sulphur disappears. The oxidation of the potassium precovered iron surface occurs faster than that of the clean one. The layer of iron oxide is formed under the layer of the potassium atoms. When the iron surface is precovered with both potassium and sulphur, the oxygen atoms are adsorbed under the layer of sulphur atoms. Sulphur is bound with potassium and the K–S bond is stable during the oxidation.