Electron-impact excitation cross sections of neon

Abstract

To determine the direct electron-impact excitation cross sections with the optical method, one must measure all transitions out of a level, as well as the cascade into the level of interest from higher-lying energy levels. Considered here are the ten levels of the ${2p}^{5}3p$ configuration of neon, whose emissions to lower levels fall within a range of 540--810 nm. This allows an investigation via a monochromator-photomultiplier tube system. Cascades into these levels from ${2p}^{5}4s$ and ${2p}^{5}3d,$ however, emit radiation in the 740--1720-nm range, part of which is outside the limit of photomultiplier detection. We employ a Fourier-transform spectrometer to examine the near-infrared lines. We report direct electron excitation cross sections for the ten ${2p}^{5}3p$ levels for electron energies up to 200 eV. In addition, we provide apparent excitation functions for the ${2p}^{5}4s$ and ${2p}^{5}3d$ levels. We have also observed a dependence of the optical emission cross sections on pressure, and describe this effect within the framework of the resonance radiation reabsorption model.