Autoionization cross section of Rb atoms excited by low-energy electron impact

The autoionization cross section of rubidium atoms excited by electrons in the energy range from the 4p6 lowest autoionization threshold to 30 eV was investigated for the first time. The data were obtained by summarizing the normalized intensities of lines in ejected-electron spectra measured at 54.7° observation angle. By analyzing the calculated energies, decay rates and excitation cross sections for the lowest autoionizing configurations it was found that the two dominant maxima of the cross section at 16 and 25 eV represent contributions from 4p55s2 doublet and 4p55s5p, 4d5s, 4d2 quartet autoionizing levels, respectively. A comparison of the data is made with the ionization cross section of rubidium atoms by electron impact.