Screening and configuration-interaction effects in the 5p x-ray--photoelectron spectrum of Th metal

This paper reports unusual structures in the x-ray photoelectron spectrum of the 5p level of thorium metal and proposes that the low-lying empty 5f levels are responsible for such a complicated 5p spectrum through two mechanisms: (i) fluctuations of the core hole between 5p and 5d25f configurations (underline denotes a hole level) and (ii) shake-up from filled valence levels to empty low-lying 5f levels