Auger Electron Spectroscopy Study of the Chemisorption of Iodine on Zirconium

Abstract

Auger electron spectroscopy was used to observe the relative coverage of iodine on the surface of a zirconium crystal exposed to a flux of iodine gas molecules. The zirconium was heated to temperatures of 1000–1300 K, and the iodine pressures corresponded to 10−4–10−6 Pa (10−9–10−11 atm). Iodine was found to chemisorb on the surface; the isotherms corresponded to the Temkin model. Isoteres derived from these isotherms showed a logarithmic dependence of pressure on reciprocal temperature. The slopes of the isoteres indicated an enthalpy of formation of the surface layer of about 60 kcal/mole. The thermodynamics of formation of an iodine adspecies on a zirconium surface were compared with the thermodynamics of formation of zirconium monoiodide, the lowest solid iodide of zirconium.