Dissociative Excitation of Vacuum Ultraviolet Emission Features by Electron Impact on Molecular Gases. I. H2 and O2

Abstract

The Hi ${\text{(2p}}^1{\hspace{0.17em}}^2{\text{P\hspace{0.17em}→\hspace{0.17em}1s}}^1{\hspace{0.17em}}^2\mathrm{S)}$ 1215.67 Å‐Lyman‐alpha line and the Oi ${\text{(3s}}^1{\hspace{0.17em}}^3{S}^0{\text{\hspace{0.17em}→\hspace{0.17em}2p}}^4{\hspace{0.17em}}^3\mathrm{P)}$ 1302.17, 1304.87, 1306.04‐Å multiplet have been excited by electrons impacting on H₂ and O₂, respectively. Their excitation cross sections have been measured over the energy range from threshold to 350 eV. The cross section for dissociative excitation of Lyman alpha has a peak value of 1.23 × 10⁻¹⁷ cm² ± 11%, while the cross section for the Oi 1300‐Å multiplet has a maximum value of 3.8 × 10⁻¹⁸ cm² ± 17%. The cross section for dissociative excitation of the Oi ${\text{(3s}}^1{\hspace{0.17em}}^1{P}^0{\text{\hspace{0.17em}→\hspace{0.17em}2p}}^4{\hspace{0.17em}}^1\mathrm{S)}$ 1217.6‐Å line is 1.5 × 10⁻¹⁹ cm² ± 24% at 100 eV.