Stability and Size of ZEKE States

Experiments on the photoionization of benzene and benzene clusters show very long lived molecular states above the ionization threshold. These states can further absorb photons to produce highly excited neutrals which maintain their Rydberg character even after fragmentation. These long lived ZEKE states also can undergo collision with simultaneously produced ions and transfer the ZEKE electron. The experiments show very large cross sections for high n Rydberg states, but still give only a minor contribution and hence can be usually neglected in typical ZEKE experiments at moderate laser intensities.