Diffusion of samarium into iridium from an incident flux of samarium atoms onto iridium coated with a graphite monolayer

A study by the method of thermal-desorption spectroscopy has revealed an effective diffusion of Sm atoms into Ir(111), which is stimulated by a graphite monolayer on the iridium surface. It is shown that the diffusion efficiency is greater by a factor of ∼10⁶–10⁷ in the presence of a graphite monolayer on iridium than in the absence of this layer. The energy of activation for the diffusion of Sm atoms into and from iridium has been found to be E = 5.5 eV and E = 6.3 eV, respectively. Iridium strips with a samarium-saturated nearsurface layer can be used as efficient sources of Sm ions (or Sm atoms), with the flux density varying in the range of 4 × 10⁹ cm⁻² s⁻¹ 〈 ν 〈 3 × 10¹¹ cm⁻² s⁻¹ as the temperature of the strip varied from 1830 to 2110 K. If the temperature of the strip remains unchanged, the flux of Sm is maintained constant for many hours. After contact with the ambient atmosphere and evacuation of air, the samarium-saturated iridium strip is still serviceable as a source of samarium.