Matrix Effects on the Electronic Partitioning of Iron Atoms Desorbed from Surfaces by Energetic Ion Bombardment

The effect of the sample matrix on the electronic partitioning of sputtered Fe atoms Is examined. The surfaces studied are clean and air-exposed polycrystalline Fe, Nl₃Fe (111) and NBS 1264a steel. In contrast to the yield of secondary Fe⁺ (which for all samples is Increased dramatically by surface contamination), the fraction of ejected ground state Fe atoms is relatively Insensitive to surface contamination. When the clean targets are subjected to 900-eV argon ion bombardment, the populations of ejected metastable excited state Fe atoms are characterized by near-Boltzmann distributions with effective temperatures of about 700 ± 100 K. The populations of Fe atoms sputtered from the air-exposed surfaces are also near-Boltzmann in character, with effective temperatures up to 1400 ± 200 K.