On the Long-Lived Excited State of Ar II

Time-of-flight energy spectra of Ar atoms produced through charge transfer reactions in collisions of Ar + (metastable Ar M+ ) ions with Ne atoms have been measured at a collison energy of 50 eV. Two prominent peaks appear at exoergicities of about 0.35 and 1 .5 eV. The measurement of the appearance energies of these peaks suggests that the 0.35 eV peak is due to metastable 3d' 2 F 7/2 ions and that the 1.5 eV peak is an indication of the existence of an unknown long-lived excited Ar + state.