Near-threshold study of the polarization of rare-gas resonance radiation: Neon

The linear polarization of resonance vacuum-ultraviolet radiation emitted by electron-impact excited Ne atoms has been measured in the energy range from threshold to 21 eV. An electron resolution of 80 meV has enabled the effects of negative-ion resonances on the polarization function to be examined in some detail. Predictions of the effects of negative-ion resonances on the observed polarizations have been made using a generalized Baranger-Gerjuoy theory. Excitation via electron exchange is shown to be the dominant process very close to threshold. {} 1996 The American Physical Society.