Aggregation state effect in Auger spectroscopy. The fluorine KLL spectrum of KF

We show by extensive Green’s function calculations that the fingerprinting double peak observed in the title spectrum of the crystal is a pure nonatomic aggregation state effect, not to be seen in the gas phase spectrum. We clarify the mechanism for this effect as being due to the energy shift of hole-localized states induced by the crystal field and their strong mixing with close lying, otherwise Auger inactive, states. The generality of the phenomenon is discussed, identifying cases where it could be observed in the gas phase and not in the crystal.