Near-threshold structures in electron-collision-induced alignment of core-excited atomic states

Structures, likely due to negative-ion resonances, are predicted in the electron-impact-induced alignment of the Na*(2p⁵3s²)²P3/2 autoionizing state near the excitation threshold. The predictions are supported by measurements of the alignment via the anisotropic emission of the autoionization electrons in the impact energy range from threshold to 80 eV. Our R-matrix (close-coupling) calculations successfully reproduce the broad-scale energy dependence of the alignment that, above the resonance region, is found to be similar to that for the valence-excited (2p⁵3s)¹P₁ state in Ne.