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

Abstract

We have measured in the laboratory the electron impact emission cross sections for O₂ at 200 eV. 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 (OI, OII, OIII). Additionally we have measured the excitation functions from 0 to 400 eV for characteristic OI multiplets at 98.9 and 102.6 nm and for OII multiplets at 53.9 and 83.3 nm. We find the OI multiplets are formed near the dissociation limit whereas the OII multiplets have a threshold about 10 eV above the dissociation limit. We also determine the total VUV emission cross section of O₂ from 40 to 200 nm and indicate the effects of autoionization to the measured emission spectrum.