A study of the extreme ultraviolet spectrum of O2 by electron impact

The electron impact emission cross sections for O2 at 200 eV have been measured in the laboratory. Included in the study are all emission features in the extreme ultraviolet from 40 to 131 nm at a resolution of 0.5 nm. The features are entirely from the dissociation products (O I, O II, O III). Additionally, the excitation functions from 0 to 400 eV have been measured for characteristic O I multiplets at 98.9 and 102.6 nm and for O II multiplets at 53.9 and 83.3 nm. It is found that O I multiplets are formed near the dissociation limit whereas the O II multiplets have a threshold about 10 eV above the dissociation limit. The total VUV emission cross section of O2 is determined from 40 to 200 nm and the effects of autoionization to the measured emission spectrum are indicated.