A photoelectron and double photoionization study of the valence electronic structure of 1,4-bromofluorobenzene

Conventional photoelectron and time-of-flight photoelectron-photoelectron coincidence (TOF-PEPECO) spectra have been measured for the outer valence region of the 1,4-bromofluorobenzene molecule. The photoelectron spectra were recorded using HeIα radiation from a resonance source, and the TOF-PEPECO spectra were recorded using HeIIα radiation from a pulsed resonance source. The former provide energies of the cationic states and the latter of the dicationic states. The spectra are adequately interpreted with the aid of accurate Green's function calculations, showing very significant correlation effects. The lowest double ionization energy is found at 23.45 eV associated with the (4b 1)-2X1A1 dicationic state. © 2009 American Institute of Physics.