DIFFERENTIAL CROSS-SECTIONS FOR ELECTRON-IMPACT EXCITATION OF XE .1. EXCITATION OF THE 5 LOWEST LEVELS - EXPERIMENT AND THEORY

Experimental and theoretical differential cross sections (DCSs) for el ectron impact excitation of the five lowest levels of xenon are report ed. The experimental data were obtained at impact energies of 10, 15, 20 and 30 eV for scattering angles in the range of 0 degrees to 135 de grees. The scattering intensities for excitation of various levels wit h respect to that of the combined two lowest levels (representing the corresponding DCS ratios) were measured with conventional electrostati c electron energy-loss spectrometers. Absolute DCSs for excitation of the combined two lowest levels were derived from DCS ratios for excita tion of the combined two lowest levels and elastic scattering and util izing the elastic DCSs of Register et al. These DCS ratios were obtain ed from scattering intensity ratios measured with conventional electro static electron energy-loss spectrometers after correction for instrum ental effects by utilizing electron time-of-flight measurements for de termining the proper value of this ratio at 90 degrees scattering angl e for each impact energy. The unitarized first-order many-body theory and the unitarized distorted-wave approximation were applied to obtain the theoretical differential cross sections for impact energies of 10 , 15, 20, 30, 50 and 80 eV. The present experimental and theoretical r esults are compared with each other and with other available experimen tal and theoretical DCSs.