Study of positron trapping at quantum-dot like copper particles on the surface of iron using positron annihilation induced auger electron spectroscopy

Annihilation studies performed in bulk Fe-Cu alloy have demonstrated the trapping of positrons in quantum-dot like Cu nano-particles in Fe. This thesis presents the results of studies of sputtered surfaces of these materials using Positron annihilation-induced Auger electron spectroscopy (PAES). In PAES energetic electron emission results from Auger transitions initiated by annihilation of core electrons with positrons trapped in a surface-state. The Cu PASS intensities obtained from different films by deposition of Cu/Fe-Cu (quenched) alloy revealed that the 95% of Cu intensities come from the 0.56A of Cu/Fe-Cu (quenched) alloy. This suggests that the implanted positrons are trapped at Cu sites in the top most layer of the sample. The low Cu intensity observed in PAES measurements of the Cu-Fe (2h-aged) alloy is consistent with trapping of positrons implanted at low energies in Cu nano particles below the surface rather than at surface site.