Measurements of nitrogen atom loss probability versus temperature on iron surfaces

Late Ar-N-2 post-discharges are used to measure the loss probability, gamma , of N atoms on iron surfaces. As no sputtering occurs in post-discharges, iron foils are probably oxidized. As the plasma is on, a transient effect i s observed on the foil surface, which is correlated to the cleaning of the surface. By means of a numerical model, gamma on Fe2O3 is deduced from expe rimental measurements: gamma(N) = (58.1+/-8.0) exp(-26940+/-2495 / RTs) As gamma(/Fe4N) is expected to be much lower than an the oxide when T varie s from 300 to 823 K, the evolution of gamma on iron foils in this range of temperature should help in following the phase transition from the oxidized to the nitrided surface state. (C) 1999 Elsevier Science S.A. All rights r eserved.