Loss for photoemission versus gain for Auger: Direct experimental evidence of crystal-field splitting and charge transfer in photoelectron spectroscopy

We find a 5 eV satellite in the Ti0.16em0ex1s photoelectron spectrum of the transition-metal oxide SrTiO₃. This satellite appears in addition to the well-studied 13 eV structure that is typically associated with the Ti0.16em0ex2p core line. We give direct experimental evidence that the presence of two satellites is due to the crystal-field splitting of the metal $3d$ orbitals. They originate from ligand 2p0.16em0ext2g→metal0.16em0ex3d0.16em0ext2g and ligand 2p0.16em0exeg→metal0.16em0ex3d0.16em0exeg monopole charge-transfer excitations within the sudden approximation of quantum mechanics. This assignment is made by the energetics of the resonant and high-energy threshold behaviors of the Ti0.16em0exK-L₂L₃ Auger decay that follows Ti0.16em0ex1s photoionization.