Observation of the Transition from the Adiabatic to the Sudden Regime for theM3M4,5M4,5(G1)Auger Excitation in Zinc

It has been observed that the photoexcited $M_3{M}_{4,5}{M}_{4,5}\left({}_{}{}^1{}_{}{}^{}G\right)$ Auger line in Zn asymmetrically broadens to lower energy with increasing photon energy. The broadening can be described by a change in the asymmetry parameter $\Delta \alpha =0.09\mathrm{}$ in a Doniach-Sunjic line shape. This is the first evidence for the transition from the adiabatic to the sudden regime in a solid. The onset of this change ∼14 eV above threshold is related to $3d$ screening electron excitations which are seen as $3p$ core-level satellites.