Low-energy Auger electron spectroscopy of clean and oxidized Cu(100) and Fe/Cu(100) surfaces

The background subtraction method for undifferentiated Auger spectra proposed by Peacock is shown to be reliable for the low‐energy Fe and Cu MVV peaks. This is illustrated by the good results obtained for spectra of clean and oxidized Cu(100), Cu(100) containing 0–5 monolayers of Fe and oxidized surfaces. This variety of surfaces made it possible to test the method on spectra with overlapping peaks of different heights and on spectra in which the peak shape changed. The spectra of the unoxidized Cu (100)/Fe surfaces could be described by weighted sums of the pure Cu and Fe MVV peaks. The background intensity at energies higher than the Cu peak could be used as an internal calibration factor for the spectra. These results are used to calculate the inelastic mean free paths for the Cu and Fe MVV electrons, which were 0.36 ± 0.07 and 0.44 ± 0.09 nm, respectively. For the oxidized surfaces the Fe (oxide) peak could be extracted by a simple subtraction of a pure Cu MVV peak. This Cu peak apparently did not change shape upon oxidation.