An analysis of the coincidence L2-L3M4,5 Coster-Kronig preceded Auger decay spectra of Fe and Co and the related Auger-Auger electron coincidence spectroscopy (AACS) spectra

It is shown by a many-body theory that when the delocalization time of the M4,5 hole created in Fe (or Co) by the L2-L3V (V = M4,5) Coster-Kronig (CK) decay is much shorter than the L3-hole lifetime, the coincidence (or singles (noncoincidence)) L2-L3V-L3-VV Auger electron spectroscopy (AES) main line of Fe (or Co) coincides in line shape and peak KE with the intrinsic singles L3-VV one. This is also the case with the Auger decay following the L1-L2,3V CK decay or the L1V (or L2,3V) shakeup/off excitations. Thus, there is no line shape change with photon energy in the singles L3-VV AES main line of Fe (or Co). In the light of the delocalization of the M4,5 hole we analyzed the experimental singles and coincidence L2,3-VV AES spectra of Fe and Co. The L3 photoelectron background intensity beneath the singles L2 photoelectron spectroscopy (PES) main line is found to be as large as the intrinsic singles L2 PES main line one. The relative intensity of the coincidence CK preceded AES spectrum to the coincidence L2-VV one of Fe increases by a factor of about 2.7 because of the Auger electrons collected in coincidence with the L3 photoelectrons in the background beneath the singles L2 PES main line. A subtraction of the background appropriate respectively for the coincidence AES (or PES) spectrum and the singles one is necessary to compare the two spectra. We discussed the prospect of determining by Auger-Auger electron coincidence spectroscopy (AACS) the charge transfer (CT) screening time or the delocalization time of the valence-hole in a doubly ionized state using as an internal clock the lifetime of a core hole in the same doubly ionized state. We analyzed the Mn M2,3V-VVV and Mn M2,3M2,3-VVVV AACS spectra of MnO. The present analysis of the Mn M2,3V-VVV AACS spectrum of MnO measured in coincidence with the singles Mn L3-M2,3V AES peak shows that the delocalization time of the valence hole in the doubly ionized state in MnO is shorter than the L2,3-hole lifetime but longer than the M2,3 one.