A method for determining intrinsic shapes of overlapping spectral lines in Auger-photoelectron coincidence spectroscopy

We present a general technique to assess and remove unwanted contributions from closely spaced features in spectra acquired using Auger-photoelectron coincidence spectroscopy. We use the Ag 3d(5/2) and 3d(3/2) core levels and their associated core valence-valence Auger decays, the Ag M5VV and M4VV Auger lines, to demonstrate this technique. Ag M5VV and M4VV Auger spectra were obtained in coincidence with 3d(5/2) and 3d(3/2) core photoelectrons, respectively. We have also measured the 3d(5/2) and 3d(3/2) core level spectra in coincidence with M5VV and M4VV Auger electrons. In the coincidence spectra, the contribution from the spin-orbit partner is considerably reduced but, in general, not eliminated. However, by measuring all four coincidence spectra, enough information is obtained to unambiguously assess and remove the unwanted contributions and thus determine the intrinsic line shape of the M5VV and M4VV Auger lines. As a cross-check of this subtraction technique, we find that the intrinsic M5VV and M4VV line shapes give an excellent account of the conventional, noncoincidence Ag M4,5VV spectrum with the expected 6:4 ratio. The correction technique described here can be applied to a large number of systems where the close separation of core lines produces additional spectral features in the coincidence measurements of their associated Auger spectra. (C) 2000 American Institute of Physics. [S0034-6748(00)01204-1].