Vacuum ultraviolet fluorescence excitation spectra of jet cooled ICl have been recorded between 158 and 166 nm using a VUV ‘‘laser’’ generated by four-wave sum-mixing in Mg vapor. An unambiguous vibrational analysis of the spectra has shown that transitions from v″=0 of the ground state probe high vibrational levels of the first tier EO+ ion-pair state between v′=245 and 360. Molecular constants obtained from both Dunham and near dissociation expansions are presented. Strong intensity modulation of the spectra was observed. Possible reasons for this effect are discussed.