Excitation coefficients of O I (2p3 (4S0)3p) level by electron and fast neutral swarms

In this work we present the spatial distributions and excitation coefficients for the level O I 2p33s–2p3(4S0)3p (leading to λ = 777.4 nm transition), produced by dissociative excitation by electron swarms in oxygen. We used a simple parallel plate drift tube and obtained absolute emission intensities in a low-current self-sustained Townsend type discharge. The data were obtained between moderate E/N (E—electric field, N—gas density) where electrons are in equilibrium and very high E/N where electrons may not be in equilibrium with the field and where heavy particles may be the dominant contributor to the excitation. Even at moderate E/N heavy particle effects become considerable.