Polarization studies of rare-gas resonance radiation: Argon, krypton, and xenon

The linear polarization of resonance vacuum-ultraviolet (VUV) radiation emitted by electron-impact excited Ar, Kr, and Xe atoms has been measured in the energy range from threshold to 480 eV using two sets of apparatus. The first apparatus measured the polarization function in the near-threshold region using an energy selected electron beam with a resolution of 160 meV. This enabled the effects of negative-ion resonances on the polarization function to be examined in 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 a significant process very close to threshold. The second apparatus used an electron beam with {~}1 eV resolution to probe the broad features of the VUV polarization functions over the energy range from threshold to 480 eV. Measurements are compared with other published data. {} 1996 The American Physical Society.