Ejected-electron excitation functions ofautoionizing states in lithium atoms

Abstract

The ejected-electron excitation functions of the lowest-lying autoionizing states (1s2s2) 2S, (1s2s2p) 4P1/2,3/2, 1s(2s2p 3P) 2P and 1s(2s2p 1P) 2P in lithium atoms have been measured for the first time at the magic angle of 54.7°. The measurements have been performed at the energy resolution of 0.4 eV over the electron impact energy range from the excitation thresholds up to 600 eV. In all excitation functions the strong resonance structures are revealed just above the excitation thresholds and in the high-impact energy region. The near-threshold structures are tentatively assigned to the shape resonances and autodetaching states of the lowest-lying 1s2s2p2, 1s2s2p3s, 1s2s2p3p and 1s2p3 Li- configurations. Above 61 eV the radiative cascade transitions from the upper autoionizing levels are considered to interpret the data. The results obtained point out the important role of negative-ion resonances in the near-threshold excitation of autoionizing states in lithium atoms.