Electron-impact ionization-excitation of the neon valence shell studied by high-resolution electron-momentum spectroscopy

Abstract

We present experimental and theoretical results for electron-impact-induced ionization and excitation of the neon valence shell by using a highly sensitive and high-resolution ($e, 2e$) spectrometer. The controversies in previous electron momentum spectroscopic results have been resolved. The satellites at 55.83 and 71.50 eV are mainly attributed to a ${\phantom{\rule{4pt}{0ex}}}^{2}P$ manifold, and mixed up with some ${}^{2}S$, not a pure ${}^{2}S$ as were assigned by the earlier electron-momentum spectroscopy. Our experimental momentum distribution for the satellite at 55.83 eV is consistent with that reported by Watanabe et al. [J. Electron Spectrosc. Relat. Phenom 142, 325 (2005)], but not consistent with Samardzic et al.'s results [Phys. Rev. A 48, 4390 (1993)]. The difference between the observed momentum distribution of the satellite at 55.83 eV and the calculations with the plane-wave impulse approximation suggests the need for further improvement of the theoretical methods.