Resonant structure in near-threshold electron excitation of krypton

By using a monochromator-analyzer combination, electron-excitation functions of the lowest-lying electronic states of krypton have been obtained at a scattering angle of 45 ° in the near-threshold region (9-14 eV). All excitation functions display a complex resonant structure. Additional data have been obtained on elastic scattering at 45 ° to provide further information on the resonances. In addition to the 4p⁵5s² J=3/2,1/2 resonance doublet, a number of narrow resonances appear below about 12 eV in both the excitation data and elastic scattering which correlate in energy with recent measurements on transmission by Sanche and Schulz. Broad resonant structure is found in a number of the excitation curves and the excitation process in the near-threshold region appears to be dominated by resonant effects. An analysis of the elastic-scattering data on the $4{p}^{5}5{s}^{2}$ doublet is presented and resonance parameters obtained compared with theory. A comparison of the narrow resonant structure data with optical absorption data on Rb I obtained by Beutler indicates that the narrow resonances in the 10.5-12-eV region are probably due to levels of the $4{p}^{5}5s4d$ configuration.