Formation of O3/+/ by the reaction of metastable O2/+/ ions with O2

The high resolution of the photoionization mass spectrophotometer was utilized to resolve some doubts about the participating species in the reaction of metastable oxygen molecular ions with oxygen molecules to yield ozone ions and oxygen radicals. It is found from inspection of the appearance potential of the ozone ion that an a4 Pi-excited state is responsible for the formation of ozone near the appearance potential of these lines.