Faculté des sciences

## New light on the Kr⁻(4p⁵5s²) Feshbach resonances: high-resolution electron scattering experiments and B-spline R-matrix calculations

### In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2010, vol. 43, no. 8, p. 085206

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 Kr⁻($4p^5 5s^2$) 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... More

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 Kr⁻($4p^5 5s^2$) 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 Kr⁻($4p^5 5s^2 ^2$ $P_{3/2}$) resonance was carried out, resulting in a resonance width of Γ3/2 = 3.6(2) meV. By direct comparison with the position of the Ar⁻($3p^5 4s^2 ^2P_{3/2}$) resonance, the energy for the Kr⁻($4p^5 5s^2 ^2P_{3/2}$) resonance was determined as E3/2 = 9.489(3) eV. A Fano-type fit of the higher lying Kr⁻($4p^5 5s^2 ^2P_{1/2}$) resonance yielded the resonance parameters Γ1/2 = 33(5) meV and E1/2 = 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 $4p^5$ ,5s excitation. They provide the total and angle-differential cross sections for excitation of long-lived and short-lived levels of the $4p^5$, 5s configuration in Kr and branching ratios for the decay of the Kr⁻($4p^5 5s^2 ^2P_{1/2}$) resonance into the three available exit channels. The results are compared with selected experimental data.