Determination of the Decay Channel of the4d→4fResonance in Tm

Abstract

We have found that the shape of the potential for $4f$ electrons in Tm predicts quite well the character of the $4d\to 4f$ autoionization resonance observed in the photoelectron spectra. The direct photoemission from the $4d$ shell is suppressed by a barrier in the potential. Tunneling through this barrier is significantly slower than the decay of the excited electron back into the $4d$ hole. This decay is thus the dominant channel and is observed to lead predominantly to autoionization of the $4f$ shell.