The VUV emission spectra have been absolutely measured in collisions between Ar+ and He, Ne, Xe by using LHT-30 Monochromator. The ionization excitation processes of incident ions and target atoms have been observed. The "promotion" of electron of molecular orbit model of Fano and Lichten, and adiabatic MO correlation diagram have been introduced. We have made attempt to work out some qualitative explanation.