Core-electron excitations and the electronic decay of core-to-bound-state transitions in condensed azabenzenes

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Abstract
We have measured N 1s near edge absorption spectra and the kinetic energy distribution of electrons emitted in the decay of N 1s core‐to‐bound‐state excitations in condensed pyridine, pyrazine, and s‐triazine. The electron emission spectra generated in the electronic decay of the core to bound state resonances lead to singly charged, participator‐type molecular final states, equivalent to the final states populated in photoemission, as well as to double hole (Auger) spectator‐type final states screened by the presence of a π spectator electron. The deexcitation spectra, therefore, give insight into charge–transfer and screening processes in the initial core‐electron excited state, as well as in the final spectator double‐hole states. One of the most prominent participator features observed in the spectra of pyridine, pyrazine, and s‐triazine is due to the emission of the most strongly bound π electrons, reflecting the dynamic screening of the core hole in the aromatic azabenzene molecules. The spectator states, on the other hand, exhibit a much reduced screening energy shift compared to linear molecules due to the delocalized nature of the π spectator electron.