Complex sentence: These non-Paulian states can be identified by the characteristic X-rays emitted during Pauli Exclusion Principle-prohibited atomic transitions to the ground state: a third electron arriving on the 1s level.
Split into simpler sentences: These non-Paulian states can be identified by the characteristic X-rays emitted during Pauli Exclusion Principle-prohibited atomic transitions to the ground state. An example for a transition of this kind would be a third electron arriving on the 1s level.