Observation of unusually enhanced satellite band in Penning-ionization electron spectra of benzene and toluene

Abstract
A strong satellite band is observed in the electron spectra of gaseous benzene and toluene obtained by impact of He*(23S) metastable atoms, although the corresponding band has not been found in ultraviolet and x-ray photoemission spectra. The band is assigned to the lowest-lying satellite (2 A2y for benzene) predicted previously by many-body calculations, its position being located for the first time. The mechanism for the band enhancement is discussed on the basis of the autoionization process.