Electron-impact excitation cross sections of neon

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.