New light on the Kr−(4p55s2) Feshbach resonances: high-resolution electron scattering experiments andB-splineR-matrix calculations

In a joint experimental and theoretical effort, we carried out a detailed study of electron scattering from Kr atoms in the energy range of the low-lying Feshbach resonances. Absolute angle-differential cross sections for elastic electron scattering were measured over the energy range 9.3–10.3 eV with an energy width of about 13 meV at scattering angles between 10° and 180°. Using several sets of elastic scattering phase shifts, a detailed analysis of the sharp resonance was carried out, resulting in a resonance width of Γ 3/2 = 3.6(2) meV. By direct comparison with the position of the resonance, the energy for the resonance was determined as E 3/2 = 9.489(3) eV. A Fano-type fit of the higher lying resonance yielded the resonance parameters Γ 1/2 = 33(5) meV and E 1/2 = 10.126(4) eV. In order to obtain additional insights, B -spline R -matrix calculations were performed for both the elastic and the inelastic cross sections above the threshold for excitation. They provide the total and angle-differential cross sections for excitation of long-lived and short-lived levels of the configuration in Kr and branching ratios for the decay of the resonance into the three available exit channels. The results are compared with selected experimental data.