The near-ultraviolet and visible emission spectrum of O2 by electron impact

Abstract

The calibrated, optically thin emission spectrum of O2 gas from 2220 to 6600 Å was measured in a crossed-beam experiment with a 100 eV electron beam. The low resolution spectrum (4.6 Å FWHM) includes emission features from the first (b4Σg− → a4Πu) and second (A2Πu → X2Πg) negative band systems of O+2 as well as from O I and O II atomic dissociation products. The excited atomic fragments are found in high lying states that contribute to the strong UV multiplets via cascading. Emission cross sections were obtained for these atomic and molecular features and compared to previous work. The excitation function for the (1, 0) vibrational transition in the first negative band was obtained from the threshold to 400 eV. The excitation functions for the first and second negative band systems are presented in analytic form.