Ionization of naphthalene via the Rydberg states using a femtosecond 775Â nm pulse

► Photoelectron spectra of naphthalene using a femtosecond pulse have been measured. ► The resulting spectra reveal two ionization paths via the Rydberg states. ► These are a Freeman resonance channel and ionization through internal conversion. ► This ionization behavior is found to be clearly different from that of anthracene. ► The difference is caused by the slower internal conversion rate of naphthalene.