Experimental and theoretical study of resonant Auger decay of core-excited NO ₂

We have obtained electron decay spectra following core excitation of NO ₂ below both the nitrogen and the oxygen K-edges. The resonant decay through participator processes is weak below the N K-edge, while is more intense below the O K-edge. The propensity rule stating that two valence electrons tend to participate in the decay with opposite spins was verified in the decay of the O1s → 6a ₁ core-excited state and the O1s → 2b ₁ core-excited state(s). Theoretical findings suggest that the relative ordering of the exchange-split core-excited components stems mainly from the valence-valence exchange interaction term being dominant over the core-valence one.