Investigating the structure of the Tin M45N45N45 auger spectrum using auger photoelectron coincidence spectroscopy

Auger photoelectron coincidence spectroscopy (APECS) data were collected for the M₄₅N₄₅N₄₅ Auger peak in coincidence with the 3p_3/2, 3d_3/2 and 3d_5/2 photoelectron lines of Tin. Model spectra were created to fit the APECS data from sets of Gaussian curves defined by Parry-Jones et al., J. Phys. C: Solid State Physics, 12 (1979) 1587. These models were then combined using information about the relative intensities of the peaks from the aforementioned paper to produce a model of the Auger peak which proved a good comparison to high resolution AES spectra. The APECS data revealed satelite structure in the M₅N₄₅N₄₅ peak in coincidence with the 3d_5/2 photoelectron line (M₅N₄₅N₄₅:3d_5/2) due to the Mg Kα₃ line of the X-ray source. There was evidence of a small Coster–Kronig component in the M₄N₄₅N₄₅:3d_3/2 data and the M₄₅N₄₅N₄₅:3p_3/2 data showed intensity in the M₄N₄₅N₄₅ and M₅N₄₅N₄₅ regions also arising from Coster–Kronig processes. The contribution of the M₄N₄₅N₄₅ plasmon was included in each of the APECS models and was reflected in the high resolution AES spectra. Slight oxidation of the surface of the sample during each 24-h period produced a 0.7 eV shift of the singles Auger peak to lower kinetic energies. The shift was not reflected in the coincidence peak which produced a spectrum of a clean surface due to the nature of the coincidence experiment.