The 4p6-core excited autoionising states in strontium: Classification and excitation dynamics

Abstract

The ejected electron spectra corresponding to the electron decay of the 4p 5 n1l1n2l2n3l3 low-lying autoionising states in strontium atoms were measured in the impact energy range from the excitation threshold of states up to 200 eV. By using the results of single-conguration HartreenFock (HF) calculations, six ejected electron lines with the lowest excitation thresholds were attributed to the decay of the (4p 5 4d5s 2 ) 3 P0;1;2 and 3 F2;3;4 autoionising states. For the 3 P1;2 and 3 F4 states the excitation functions were obtained at an incident electron energy resolution of 0.15 eV. In all excitation functions the strong near-threshold structure was revealed for the rst time. The origin of the structure was attributed to the decay of short-lived states from the 4p 5 5s 2 4d 2 conguration of Sr i ion. The cascade population of the 3 P0;1;2 and 3 F2;3;4 states was considered by using the HF energies and decay probabilities for the 4p 5 5s 2 5p levels.