Experimental high resolution study of the photoproduction of Ne+ 3p satellites in the threshold energy range

Cross sections for photon-induced production of Ne+ in the 2p4(3P)3p 2P, 4P, 2D, 2p4(1D)3s 2D and 2s2p6 2S states have been measured for energies between 52 eV and 55.5 eV. Linearly polarized undulator radiation with a bandwidth of 18 meV and 4.5 meV was used. The applied method of photon-induced fluorescence spectroscopy allows the measurement of the alignment A20 of the excited states with all fine structure components being resolved. Autoionization from doubly excited Rydberg states was observed as a dominating population mechanism, except for the 2p4(3P)3p 2PJ and the 2s2p6 2S1/2 states. These states are also populated directly, showing interference profiles in their cross section energy dependence. The remarkly direct population of the 2p4(3P)3p 2PJ states and the excitation of the 2p4(3P)3p 2P3/2,1/2 ns,nd Rydberg series can qualitatively be related to the 2p53p admixture of the Ne ground state. The measured alignment values allow an analysis of the photoelectron partial waves with respect to the dominating jel values. So far, no theoretical analysis has been carried out for comparison.