Energy shift of the (2p53s2)2P3/2 line in ejected-electron spectra of sodium atoms excited by low-energy electron impact

The energy shift of the line resulting from the decay of the (2p53s2)2P3/2 lowest autoionizing state in Na atoms has been measured in the ejected-electron spectra obtained at near-threshold electron impact energies. Contrary to the smooth asymptotic behavior predicted by the known models of the PCI effect, the data reveal pronounced oscillatory character of the energy dependence of the shift in the energy regions where the strong negative-ion resonances are present in the excitation function of the 2P3/2 state.