Resonant Auger spectroscopy of solid acrylonitrile at the N K-edge

This work is a resonant Auger spectroscopy study of solid acrylonitrile at the N K-edge. The three π* NEXAFS transitions, denoted 3a″, 13a′ and 4a″ in the C_s symmetry group of the molecule, are polarized in the molecular plane (a′ symmetry) or perpendicular to it (a″ symmetry), the highest energy transition, 4a″, being close to the ionization potential (the term value is about -1 eV). A strong selectivity with the symmetry of the probed unoccupied orbital is observed for both participator and spectator channels intensities. At the 3a″ and 13a′ NEXAFS resonances, intense participator channels and strong spectator shifts are observed, indicative of a localization of the promoted electron around the core-hole. Departures from a Raman behavior are also seen and discussed in terms of possible vibronic effects. At the third NEXAFS resonance (4a″), two spectator branches are observed with two different spectator shifts. We propose that the electron promoted to this orbital remains localized around the core hole, however it has a non-zero probability of being transferred into a more 'diffuse' level.