Resonant Auger electron–photoion coincidence study of the fragmentation dynamics of an acrylonitrile molecule

Abstract

Monochromatic synchrotron radiation was used to promote K-shell electrons of nitrogen and carbon from the cyano group (C ≡ N) of gaseous acrylonitrile (C2H3–CN) to the unoccupied antibonding π*C ≡ N orbital. Photofragmentation of acrylonitrile molecules following selective resonant core excitations of carbon and nitrogen core electrons to the π*C ≡ N orbital was investigated using the electron-energy-resolved photoelecton–photoion coincidence technique. The fragment ion mass spectra were recorded in coincidence with the resonant Auger electrons, emitted in the decay process of the core-excited states. Singly and triply deuterated samples were used for fragment identification. The results showed the initial core-hole localization to be of minor importance in determining the dissociation pattern of the molecular cation. The participator and spectator Auger transitions produce entirely different fragmentation patterns and the latter indicates that complex nuclear rearrangements take place. It is suggested that the calculated kinetic energy releases are caused by the existence of metastable states, which appear with the opening of the spectator Auger channels.