SURFACE SEGREGATION OF ARSENIC IN IRON

The surface of polycrystalline iron covered by segregated arsenic, pho sphorus and sulphur was analysed in a combined electron spectroscopic study by means of Auger electron spectroscopy (AES) and X-ray photoele ctron spectroscopy (XPS). The saturation coverage of arsenic at 1033 K was determined as 0.33 +/- 0.02 monolayer. Sulphur, arsenic and phosp horus segregate in competition. A relation giving the surface coverage from the XPS intensity of adsorbed element is deduced from the experi ments and is also calculated. Experimental and calculated values are f ound to be in relatively good agreement.